Use generated descriptors for MTP discovery

[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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• Files reviewed: 22/22 changed files
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• Review effort level: Balanced

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 0 new
• Review effort level: Balanced

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 2
• Review effort level: Balanced

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Review details

• Files reviewed: 24/24 changed files
• Comments generated: 1
• Review effort level: Balanced

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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Review details

• Files reviewed: 25/25 changed files
• Comments generated: 1
• Review effort level: Balanced

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🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

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[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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• Files reviewed: 22/22 changed files
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• Review effort level: Balanced

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Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

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• Comments generated: 0 new
• Review effort level: Balanced

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 2
• Review effort level: Balanced

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Review details

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• Comments generated: 1
• Review effort level: Balanced

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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• Comments generated: 1
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[github-actions]

🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

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[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

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• Comments generated: 0 new
• Review effort level: Balanced

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Review details

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• Comments generated: 2
• Review effort level: Balanced

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Review details

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• Review effort level: Balanced

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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• Comments generated: 1
• Review effort level: Balanced

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🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
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changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

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[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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• Files reviewed: 22/22 changed files
• Comments generated: 3
• Review effort level: Balanced

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Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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[github-actions]

🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 0 new
• Review effort level: Balanced

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 2
• Review effort level: Balanced

[Copilot]

Review details

• Files reviewed: 24/24 changed files
• Comments generated: 1
• Review effort level: Balanced

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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Review details

• Files reviewed: 25/25 changed files
• Comments generated: 1
• Review effort level: Balanced

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[github-actions]

🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

🤖 Automated content by GitHub Copilot. Generated by the Parallel-safety audit on PR (on open / sync) workflow. · auto · 112.7 AIC · ⌖ 2.11 AIC · ⊞ 24.8K · [◷]( · ◷)

[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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• Files reviewed: 22/22 changed files
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• Review effort level: Balanced

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Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

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• Comments generated: 0 new
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Review details

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• Comments generated: 2
• Review effort level: Balanced

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• Comments generated: 1
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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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• Comments generated: 1
• Review effort level: Balanced

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🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

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[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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• Files reviewed: 22/22 changed files
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• Review effort level: Balanced

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Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 0 new
• Review effort level: Balanced

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Review details

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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[github-actions]

🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

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[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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[github-actions]

🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 0 new
• Review effort level: Balanced

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 2
• Review effort level: Balanced

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Review details

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• Review effort level: Balanced

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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Review details

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• Comments generated: 1
• Review effort level: Balanced

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🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

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[Amaury Levé (Evangelink)]

Summary

Add a bounded MTP-only generated descriptor discovery path for plain synchronous [TestMethod] and [DataRow] methods.

Generated methods that declare complete support bypass the legacy runtime method enumeration and validation pass. Mixed classes fall back per method, while VSTest continues using the existing discovery path.

Old and new flow

Before:
generated registry -> MethodInfo registration -> runtime method scan/validation
-> UnitTestElement -> existing lifecycle/execution -> MTP TestNode
After (supported subset):
generated descriptor -> UnitTestElement
-> existing lifecycle/execution -> MTP TestNode
Fallback:
unsupported generated method -> existing runtime method scan/validation

This deliberately retains UnitTestElement, filtering, lifecycle, execution, and result conversion. It is the first production vertical slice, not a second lifecycle engine.

Supported subset

The fast path is limited to complete generated descriptors for public, instance, non-abstract, non-async, void methods with the exact built-in TestMethodAttribute and optional DataRowAttributes.

The legacy path remains authoritative for:

• async/Task/ValueTask methods;
• custom TestMethodAttribute implementations;
• DynamicData/custom ITestDataSource;
• incomplete or unsupported metadata;
• ambiguous overloads and mixed classes;
• VSTest.

The selection is observable internally through generated-descriptor metadata and focused path-selection tests.

Impact

Projects/layers changed:

• MSTest.SourceGeneration models and emitters expose descriptor capability.
• PlatformServices registration/provider surfaces descriptor methods.
• MTP discovery consumes supported descriptors and falls back per method.
• Existing lifecycle, TestContext, execution, retry, timeout, cleanup, filtering, and result pipelines are unchanged.

Controlled discovery benchmark, 10,000 iterations with two tests per iteration and five samples:

• allocations: 114,451,416 B -> 89,573,624 B (-21.7%);
• median elapsed: 508.162 ms -> 415.724 ms (-18.2%), but one sample regressed, so no strong wall-clock claim is made.

Release assembly size cost:

• MSTest.SourceGeneration: +8,192 B (+4.94%);
• MSTestAdapter.PlatformServices net8.0: +11,264 B (+2.13%).

Validation

• MSTest.SourceGeneration.UnitTests: 127/127 passed.
• MSTestAdapter.PlatformServices.UnitTests net8.0: 1,081/1,081 passed.
• Managed ReflectionFree acceptance: 2/2 passed (net8.0 and net10.0).
• NativeAOT acceptance: 2/2 passed.
• Release pack: succeeded with 0 warnings and 0 errors.
• Three independent reviews covered correctness, architecture/compatibility, and performance.

Future phases

This PR does not bypass UnitTestElement, TypeCache during execution, the lifecycle engine, or MTP result conversion. Follow-up work can introduce a generated execution abstraction and broader descriptor eligibility while preserving this per-method fallback boundary.

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Pull request overview

Adds an MTP-only fast discovery path using generated descriptors while preserving legacy fallback and VSTest behavior.

Changes:

• Extends source-generation metadata with descriptor eligibility and completeness.
• Uses descriptors during MTP discovery with per-method fallback.
• Adds unit, acceptance, and NativeAOT coverage.

Show a summary per file

File	Description
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/TestablePlatformServiceProvider.cs	Supports generated reflection providers in tests.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/TestableImplementations/MockableReflectionOperations.cs	Forwards descriptor lookups.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/SourceGeneration/SourceGeneratedReflectionOperationsTests.cs	Tests descriptor retrieval and completeness.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.cs	Tests fast-path selection and fallback.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTestReflectionMetadataGeneratorTests.cs	Verifies generated descriptor metadata.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/SourceGenerationNonAotTests.cs	Checks non-AOT generated output.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/NativeAotTests.cs	Checks NativeAOT eligibility metadata.
src/Analyzers/MSTest.SourceGeneration/Models/TestClassModel.cs	Adds descriptor capability fields.
src/Analyzers/MSTest.SourceGeneration/Generators/TestClassModelBuilder.cs	Determines descriptor eligibility.
src/Analyzers/MSTest.SourceGeneration/Generators/RuntimeRegistrationEmitter.cs	Emits descriptor registration.
src/Analyzers/MSTest.SourceGeneration/Generators/MetadataRegistryEmitter.cs	Emits descriptor metadata properties.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs	Exposes registered descriptors.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionDataProvider.cs	Stores descriptor data.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs	Registers descriptor metadata.
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/CompositeSourceGeneratedReflectionDataProvider.cs	Merges descriptor providers.
src/Adapter/MSTestAdapter.PlatformServices/Services/ReflectionOperations.cs	Provides reflection-mode fallback.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Tracks the new public overload.
src/Adapter/MSTestAdapter.PlatformServices/ObjectModel/UnitTestElement.cs	Marks descriptor-originated tests.
src/Adapter/MSTestAdapter.PlatformServices/Interfaces/IReflectionOperations.cs	Defines descriptor lookup.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs	Consumes descriptors during discovery.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumeratorWrapper.cs	Enables descriptors for MTP.
src/Adapter/MSTestAdapter.PlatformServices/Discovery/AssemblyEnumerator.cs	Propagates descriptor selection.

Review details

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• Files reviewed: 22/22 changed files
• Comments generated: 3
• Review effort level: Balanced

[github-actions]

Note

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Review Summary — PR #10777

This PR introduces source-generated test descriptors for native MTP discovery, allowing the discovery path to skip the legacy runtime-method scan when generated metadata is complete. The design is well-layered: the source generator emits per-method/per-class support flags, the ReflectionMetadataHook.Register overload carries the new dictionaries, and the TypeEnumerator consumes them with a clean fallback path.

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	⚠️ Merge semantics for DescriptorCompleteTypes are last-writer-wins — may silently produce wrong result when multiple providers register the same type
2	Threading & Concurrency	✅ N/A — no new shared mutable state introduced
3	Security & IPC	✅ N/A
4	Public API & Binary Compat	✅ New Register overload added (additive), old overload delegates. PublicAPI.Unshipped.txt updated.
5	Performance & Allocations	✅ Good — List pre-sized, HashSet used for skip-set
6	Cross-TFM Compatibility	✅ N/A — no TFM-specific APIs used
7	Resource & IDisposable	✅ N/A
8	Defensive Coding	✅ Null checks on new parameters, graceful fallback when descriptors unavailable
9	Localization	✅ N/A
10	Test Isolation	✅ Tests set up their own providers
11	Assertion Quality	✅ Uses AwesomeAssertions per project policy
12	Flakiness Patterns	✅ N/A
13	Test Completeness	✅ Good coverage of complete, incomplete, and non-MTP paths
14	Data-Driven Test Coverage	✅ N/A
15	Code Structure	⚠️ Minor — redundant ternary in AssemblyEnumerator
16–22	Remaining dimensions	✅ N/A or clean

Key Findings

1. MAJOR — CompositeSourceGeneratedReflectionDataProvider merge semantics: MergeInto for DescriptorCompleteTypes uses last-writer-wins. When two providers disagree on completeness for the same type, correctness depends on registration order. The safe semantic is logical AND. Same concern applies to DescriptorTestMethods (arrays should be concatenated, not overwritten).

2. Minor — Redundant ternary: The call in AssemblyEnumerator.DiscoverTestsInType could use the two-arg overload directly.

3. Minor — Name-based duplicate detection vs. signature-based: TestClassModelBuilder disqualifies overloaded methods by name, while the runtime uses ToString() (includes signature). This is conservative but worth documenting.

Overall this is a solid, well-tested addition. The merge-semantics issue (finding #1) is the only one that could cause a real bug in multi-assembly/multi-provider scenarios.

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🔍 Build Failure Analysis

Summary — The Linux Release build failed because dotnet format/analyzer style errors (IDE0306/IDE0028, promoted to build errors) fire on a new line added by this PR.

Root cause: Collection initialization can be simplified

TypeEnumerator.GetTests was modified to build descriptorMethodSet via new HashSet<MethodInfo>(descriptorMethods). The repo's style analyzers require the collection-expression form ([.. descriptorMethods]) instead of the constructor-with-argument form, so IDE0306/IDE0028 are raised and — since this repo builds with analyzers as errors — the build fails.

Affected files / errors

• src/Adapter/MSTestAdapter.PlatformServices/Discovery/TypeEnumerator.cs:99 — IDE0306/IDE0028: Collection initialization can be simplified

Proposed fix

- : new HashSet<MethodInfo>(descriptorMethods);+ : [.. descriptorMethods];

---

Build overview

• MSBuild: 18.11.0-1.26420.103+1d599674e
• Projects: 51, Errors: 7, Warnings: 1
• Failed projects: Build.proj, NonWindowsTests.slnf, MSTestAdapter.PlatformServices.csproj, MSTest.TestAdapter.csproj

All MSBuild errors (7)

Code	Project	File:Line	Message
IDE0306	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
IDE0028	MSTestAdapter.PlatformServices	TypeEnumerator.cs:99	Collection initialization can be simplified
(duplicated across multiple targets, same root cause)

---

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 0 new
• Review effort level: Balanced

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Review details

• Files reviewed: 23/23 changed files
• Comments generated: 2
• Review effort level: Balanced

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Review details

• Files reviewed: 24/24 changed files
• Comments generated: 1
• Review effort level: Balanced

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Comments that could not be inline-anchored

test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:262

🧪 Test review · Grade D (60–69) — Registers a method into the process-global ReflectionMetadataHook.Composite registry with no reset, so the registration persists across the whole test-assembly run.

Reset the registration after the test (or route registration through a disposable/mockable seam) so other tests can't observe GeneratedDescriptorTestClass as permanently registered.

Replacement: none

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Review details

• Files reviewed: 25/25 changed files
• Comments generated: 1
• Review effort level: Balanced

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🧪 Expert test review — PR #10777

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new TypeEnumeratorTests. EnumerateShouldSelectPlainAndDataRowDescriptorsWhenComplete	2/3 killed	Relies implicitly on isValidTestMethod:false to prove no fallback ran; unlike sibling tests it never asserts _mockTestMethodValidator was not invoked.	Add _mockTestMethodValidator.Verify(..., Times.Never) as the sibling tests do.
A (90–100)	new AssemblyEnumeratorWrapperTests. GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp	4/4 killed	Registers real metadata via ReflectionMetadataHook and asserts IsFromGeneratedDescriptor differs between MTP and VSTest paths, with proper Instance restore in finally.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldUseCompleteGeneratedDescriptorsWithoutLegacyMethodValidation	3/3 killed	Confirms descriptor-only path both selects the right method and explicitly verifies validator is never consulted.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldFallBackPerMethodWhenGeneratedDescriptorsAreIncomplete	4/4 killed	Verifies mixed descriptor/fallback membership, per-test IsFromGeneratedDescriptor flag, and that the validator is skipped only for the descriptor method.	—
A (90–100)	new TypeEnumeratorTests. EnumerateShouldIgnoreGeneratedDescriptorsOutsideNativeMtp	2/2 killed	Confirms the legacy Enumerate(warnings) overload never marks results as generated-descriptor sourced.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ ReturnsRegisteredMethodsAndCompleteness	3/3 killed	Directly asserts the returned method identity and completeness flag from a single provider registration.	—
A (90–100)	new SourceGeneratedReflectionOperationsTests. TryGetTestMethodDescriptors_ RetainsPerMethodFallbackWhenRegistrationIsIncomplete	4/4 killed	Exercises composite-provider merge semantics, proving completeness is AND-ed across conflicting providers.	—
A (90–100)	mod NativeAotTests. NativeAotTests_WillRunWithExitCodeZero	2/2 killed	New assertions pin IsDescriptorSupported true/false for synchronous vs async generated methods in the published registry.	—
A (90–100)	mod SourceGenerationNonAotTests. SourceGenerationNonAot_BuildsAndRunsTests_WithExitCodeZero	3/3 killed	Confirms new descriptor-support and registration-array flags are emitted end-to-end for the non-AOT reflection-free path.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ DeclaresDescriptorSupportOnlyForBoundedSynchronousSubset	4/4 killed	Uses positional substring checks to pin per-method IsDescriptorSupported for DataRow, attribute-fallback, and async cases.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InaccessibleTestMethodRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a private [TestMethod] is excluded from the registry entirely while the public sibling still gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ UnsupportedExecutionShapesRetainLegacyDiscoveryFallback	4/4 killed	Loops over static, Task-returning, ValueTask-returning, and async-void shapes and asserts each is marked unsupported.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ PartialTestClassRetainsLegacyDiscoveryFallback	3/3 killed	Verifies descriptor support is granted per-method even when the [TestClass] declaration is split across partial declarations.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ InheritedCustomTestMethodOverrideRetainsLegacyDiscoveryFallback	3/3 killed	Confirms an inherited custom TestMethodAttribute override falls back to legacy discovery while a plain sibling gets descriptor support.	—
A (90–100)	new MSTestReflectionMetadataGeneratorTests. Generator_ TestMethodAccessorRetainsLegacyDiscoveryFallback	3/3 killed	Confirms a [TestMethod] on a property accessor is excluded from the registry while a normal method sibling is supported.	—

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

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[github-actions]

🧵 Parallel-safety audit — PR #10777

Parallelization — one row per test assembly audited:

Test assembly	Scope	Workers	Analyzer coverage
MSTestAdapter.PlatformServices.UnitTests	off (uses TestFramework.ForTestingMSTest.TestContainer, which has no parallel scheduler)	n/a	n/a
MSTest.SourceGeneration.UnitTests	off (same internal test engine)	n/a	n/a
MSTest.Acceptance.IntegrationTests (NativeAotTests, SourceGenerationNonAotTests)	not determined from this diff (no [assembly: Parallelize]/[assembly: DoNotParallelize] change here)	n/a	n/a

⚠️ The two unit-test projects touched by this PR run on the internal TestContainer-based engine, which has no parallel scheduler at all. Everything below is a readiness checklist — what to fix before any such code is exercised under real MSTest parallelization — not a live race today. Severities capped at Warning.

Findings: A (global-state) 1 · B (paths) 0 · C (declaration) 1 · D (over-serialization) 0 — by severity: Warning 1 · Info 1.

Top actions (by expected value):

1. If GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp (or similar tests mutating PlatformServiceProvider.Instance) is ever ported to a real MSTest-parallel suite, keep the existing save/restore-in-finally pattern and pair it with an explicit [ResourceLock]/[DoNotParallelize] declaration rather than relying on [DoNotParallelize] alone if the goal is future MethodLevel-safe coordination.
2. No shared-filesystem-path or over-serialization issues found in the changed lines.

---

Warning (readiness)

• [A · High confidence]test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/AssemblyEnumeratorWrapperTests.cs:99-127 — new test GetTestsShouldSelectGeneratedDescriptorsOnlyForMtp sets the process-global singleton PlatformServiceProvider.Instance = null then re-registers a custom provider, mutating the same static field the constructor (:28) and Dispose (:37) of this class already set/reset per test. This is exactly the kind of process-global mutation category A flags. It is correctly declared [DoNotParallelize] (line 89) and the value is restored in a finally block (line 127), so it is well-guarded for this engine. Under the current TestContainer engine there is no scheduler so this cannot race today; it is readiness-only. Fix (if/when ported to real MSTest parallel execution): keep [DoNotParallelize] (or a dedicated [ResourceLock] key) and the try/finally restore — this is already the correct pattern, just note it explicitly rather than relying on convention, since other tests in the same file (constructor/Dispose) touch the same static without any lock declaration.

Info

• [C · Low confidence] Constructor/Dispose of AssemblyEnumeratorWrapperTests (pre-existing, not changed by this PR) set/reset PlatformServiceProvider.Instance on every test without any [ResourceLock]/[DoNotParallelize] declaration. This is pre-existing (outside the PR's changed ranges) and reported here only as context — not attributable to this PR — since this file already establishes the pattern the new test follows.

Nothing else in the changed lines (TypeEnumeratorTests.cs, SourceGeneratedReflectionOperationsTests.cs, MockableReflectionOperations.cs, TestablePlatformServiceProvider.cs, the acceptance-test assertions in NativeAotTests.cs / SourceGenerationNonAotTests.cs, and the raw [assembly: Parallelize(...)] strings embedded as source-generator test input in MSTestReflectionMetadataGeneratorTests.cs, which configure a synthetic compiled sample, not this test assembly) mutates process-global state, shared filesystem paths, or declares/removes [ResourceLock] / [DoNotParallelize] / [Parallelize] on a real assembly.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

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