Restore Polyfills.Polyfill.Deconstruct for binary compatibility (#9710)

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.

[Amaury Levé (Evangelink)]

Fixes#9710.

Problem

Upgrading to MTP 2.3.0 can throw at runtime:

System.MissingMethodException: Method not found: 'Void Polyfills.Polyfill.Deconstruct(System.Collections.Generic.KeyValuePair`2<!!0,!!1>, !!0 ByRef, !!1 ByRef)'.
at Microsoft.Testing.Extensions.Telemetry.AppInsightsProvider.<IngestLoopAsync>d__18.MoveNext()

Root cause

Older Microsoft.Testing.* extension assemblies (built before the Polyfill package switched to [Embedded] types) were compiled against Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) and — through InternalsVisibleTo — bound that call to the copy declared in the coreMicrosoft.Testing.Platform assembly. When Polyfill was dropped (#7726), that method disappeared, so pairing a newer core (2.3.0) with an older extension (e.g. an old Microsoft.Testing.Extensions.Telemetry pulled in transitively, as happens with xunit.v3.mtp-v2) fails with MissingMethodException.

Fix

Re-add the single Deconstruct extension onto the existing[Embedded] internal static partial class Polyfills.Polyfill that core already ships (in ProcessExtensions.cs). Core still grants InternalsVisibleTo to those extension assemblies under the same key, so this restores the runtime binding for already-shipped old extensions — without re-exposing the polyfill to source consumers (it stays [Embedded]). Current source is unaffected: nothing deconstructs a KeyValuePair anymore, and on .NET the framework instance Deconstruct still wins.

The method is marked [Obsolete] with a message stating it must be removed in the next major version of Microsoft.Testing.Platform. It's scoped to the method (not the whole Polyfill type) because that partial type also hosts WaitForExitAsync, which core still uses on netstandard2.0.

The consumer-side workaround from the issue (pinning Microsoft.Testing.Extensions.Telemetry to the core version) still applies; this change is a binary-compat safety net.

Verification

• PE-metadata probe confirms Polyfills.Polyfill.Deconstruct is emitted in the compiled net8.0 core DLL.
• Full build.cmd -c Debug succeeds with 0 warnings / 0 errors across all TFMs (net462/472/48, net8.0, net9.0, netstandard2.0, uap).

Note

Reintroducing removed Polyfill surface is a design call — happy to drop this in favor of a packaging-only solution if maintainers prefer.

[Copilot]

Pull request overview

This PR restores Polyfills.Polyfill.Deconstruct(KeyValuePair<,>, out, out) in the embedded Polyfills.Polyfill type to preserve runtime binary compatibility when newer Microsoft.Testing.Platform cores are paired with older Microsoft.Testing.* extension assemblies.

Changes:

• Reintroduces a single Deconstruct<TKey,TValue> extension method on Polyfills.Polyfill as a binary-compatibility shim.
• Marks the shim as [Obsolete] with guidance to remove it in the next major version.

Show a summary per file

File	Description
src/Polyfills/Polyfill.cs	Adds back Polyfills.Polyfill.Deconstruct to prevent MissingMethodException with older extension binaries.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Low

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

✅ 22/22 dimensions clean — no findings.

Summary: Well-scoped binary-compatibility shim that restores the exact method signature old extension assemblies expect (Void Polyfills.Polyfill.Deconstruct(KeyValuePair<TKey,TValue>, TKey&, TValue&)). The fix is correct because:

• The [Embedded] attribute on the partial declaration in ProcessExtensions.cs covers the whole type — no attribute needed on this new partial.
• InternalsVisibleTo from Microsoft.Testing.Platform.csproj already grants access to the affected extension assemblies (Telemetry, etc.).
• On .NET 5+, the framework's instance Deconstruct wins for source resolution; this extension is only invoked by pre-compiled old binaries via method token.
• The [Obsolete] message is clear, actionable, and references the tracking issue.
• No public API surface change — the class is internal.
• The unconditional compilation (no #if guard) is intentional and correct: old extensions target both .NET and .NET Framework, so the shim must be emitted on all TFMs.

[Amaury Levé (Evangelink)]

Closing as superseded by #9739, which fixes the same issue (#9710) but more completely:

• Restores the full set of Polyfills.Polyfill members old 2.x extensions reference (Deconstruct, Contains×2, AppendJoin×2, CopyToAsync, SaveAsync), not just Deconstruct — so every old 2.x extension loads correctly on .NET Framework, not only Telemetry.
• Guards the shim to #if !NETCOREAPP so it only lands in the netstandard2.0 asset that's actually loaded on .NET Framework.
• Adds a reproducing acceptance test (TelemetryForwardCompatibilityTests) using the oldest supported 2.0.0 extension with telemetry enabled — verified red without the shim and green with it.

One thing worth carrying over from here: the [Obsolete] "remove in next major" annotation. I'll port that intent onto #9739.