[tests] Use local servers for networking tests by simonrozsival · Pull Request #12022 · dotnet/android

simonrozsival · 2026-07-08T16:42:35Z

Summary

Replace httpbin.org redirect/decompression coverage with local loopback HTTP endpoints
Replace badssl.com self-signed/hostname-mismatch coverage with local self-signed HTTPS servers
Update LinkDesc HttpClient regression to post to a local HttpListener

Validation

make all
./dotnet-local.sh build -t:Install -c Debug tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj -p:Device=R58Y30HZ65V -p:IncludeCategories=SSL
(cd tests/Mono.Android-Tests/Mono.Android-Tests && ../../../dotnet-local.sh test Mono.Android.NET-Tests.csproj --no-build -c Debug --report-trx --results-directory ../../../bin/TestDebug/TestResults -p:Device=R58Y30HZ65V -p:IncludeCategories=SSL) — 25 passed
./dotnet-local.sh test bin/TestDebug/MSBuildDeviceIntegration/net10.0/MSBuildDeviceIntegration.dll --filter "FullyQualifiedName~InstallAndRunTests.CustomLinkDescriptionPreserve" — 4 skipped (test is currently ignored for all runtime variants)

Replace httpbin.org and badssl.com dependencies in networking tests with local loopback HTTP/HTTPS servers, including self-signed TLS coverage. Update the LinkDesc HttpClient regression to post to a local listener. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

This PR updates networking-related tests to stop depending on external internet endpoints (httpbin.org/badssl.com) by introducing local loopback HTTP/HTTPS test servers and switching existing redirect/decompression/SSL-validation tests to use them. This improves test reliability in constrained or offline environments and reduces external flakiness.

Changes:

Added reusable local HTTP/HTTPS test server helpers for Mono.Android.NET-Tests.
Migrated AndroidMessageHandler redirect/decompression and invalid-certificate tests to use local servers instead of external hosts.
Updated the LinkDesc HttpClient regression app/test to POST to a local HttpListener endpoint and adjusted the manifest to allow cleartext traffic + INTERNET permission.

Show a summary per file

File	Description
tests/MSBuildDeviceIntegration/Tests/InstallAndRunTests.cs	Enables cleartext + INTERNET permission for the LinkDesc regression app so it can talk to local HTTP endpoints.
tests/MSBuildDeviceIntegration/Resources/LinkDescTest/HttpClientTest.cs	Replaces external POST target with a local HttpListener-based loopback server.
tests/Mono.Android-Tests/Mono.Android-Tests/Xamarin.Android.Net/LocalTestServers.cs	Introduces local HTTP and HTTPS server helpers for test scenarios (compression, redirects, self-signed certs).
tests/Mono.Android-Tests/Mono.Android-Tests/Xamarin.Android.Net/AndroidMessageHandlerTests.cs	Switches decompression, redirect, and SSL callback tests to local servers.
tests/Mono.Android-Tests/Mono.Android-Tests/Xamarin.Android.Net/AndroidHandlerTestBase.cs	Updates redirect tests to use local loopback servers.
tests/Mono.Android-Tests/Mono.Android-Tests/System.Net/SslTest.cs	Removes httpbin from the external URL list to reduce dependency on that service.
tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj	Adds the new LocalTestServers.cs to the test project build.

Copilot's findings

Files reviewed: 7/7 changed files
Comments generated: 4

Bind local HTTP listeners to loopback, dispose LinkDesc HTTP resources, backdate self-signed certificates further, and assert policy errors in the HTTPS redirect callback test. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Share local test server exception handling and shutdown logic, and add intent-level helpers for redirect and OK responses to remove repeated listener setup in networking tests. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Add local HTTP test-server endpoint helpers for the networking tests and LinkDesc HttpClient regression. Scope the generated app's cleartext allowance to localhost via network security config instead of enabling app-wide cleartext traffic. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Use declaration-style using statements in the local HTTP test helpers and redirect tests to reduce nesting. Opt the generated LinkTestLib project into C# 8 so its embedded helper can use using declarations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove the extra LocalHttpTestServer wrapper from Mono.Android networking tests. LocalTestServer now owns shared lifecycle/error handling, LocalHttpServer owns HTTP listener behavior and test endpoints, and LocalHttpsServer remains the HTTPS/self-signed transport helper. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Replace the Mono.Android HttpListener-based LocalHttpServer with a TCP-based request parser/router shared by LocalHttpsServer. HTTPS now exposes the same /ok and /redirect-to endpoints as HTTP, with TLS layered via SslStream. Rename the generated LinkDesc helper to LinkDescHttpServer to avoid confusion with the Mono.Android helpers. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Use BaseAddress with httpbin-style relative redirect endpoints in networking tests, name the HTTPS certificate host argument, and rename the generated LinkDesc helper back to LocalHttpServer with a /post endpoint. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Remove the duplicate LinkDesc local HTTP server and compile the shared Mono.Android LocalTestServers helper into the generated LinkTestLib project. Make the shared helper netstandard2.0-compatible for the LinkDesc library while keeping HTTPS/Brotli support for the Mono.Android tests. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival · 2026-07-09T21:28:12Z

/review

github-actions · 2026-07-09T21:28:56Z

✅ Android PR Reviewer completed successfully!

github-actions

🤖 Code Review — ⚠️ Needs Changes

Nice cleanup. Replacing httpbin.org / badssl.com with in-process loopback servers removes a real source of external-network flakiness, and LocalTestServers.cs is well thought through:

Per-response Connection: close correctly forces a fresh TLS handshake, which is what keeps ServerCertificateCustomValidationCallback_Redirects asserting callbackCounter == 2.
Handler exceptions are captured off the accept loop and surfaced via AssertNoUnhandledExceptions(), and dispose-time IOException/ObjectDisposedException are correctly ignored once the handler completed.
Self-signed cert generation with SANs and the HTTPS host pinned to localhost (matching the cert) is a sensible design.

CI: ✅ All dotnet-android checks are green on bd7911c. mergeable_state: blocked reflects the pending maintainer review, not a CI failure.

Findings (see inline):

⚠️ 1 warning — LinkDesc network_security_config.xml whitelists cleartext for localhost, but LocalHttpServer uses 127.0.0.1; the LinkDesc HttpClientTest will hit Cleartext ... not permitted once CustomLinkDescriptionPreserve is un-ignored.
💡 2 suggestions — port-selection race in GetAvailablePort() (re-introduces a flaky window); reduced fidelity of NoServerCertificateCustomValidationCallback_ThrowsWhenThereIsCertificateHostnameMismatch.

Worth double-checking before merge: the two tests that actually exercise the loopback servers end-to-end aren't part of the green CI legs — CustomLinkDescriptionPreserve is ignored for all runtime variants (per the PR description), and the SSL-category AndroidMessageHandlerTests run on a physical device rather than the emulator legs. So the green checks above don't fully validate the new cleartext/loopback paths.

Prioritized: the network-security-config vs. server-host mismatch is the one to fix; the other two are optional.

Generated by Android PR Reviewer for #12022 · 209.6 AIC · ⌖ 27.5 AIC · ⊞ 6.8K
_{Comment /review to run again}

Bind local test listeners directly to ephemeral ports and align the loopback cleartext configuration. Trust the local certificate before asserting a hostname mismatch so the test isolates name validation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 9721cbaf-7e53-4fb0-b12c-6c9de7483f9d

> Re-opened as a direct PR (supersedes #12098) so the `dotnet-android` pipeline runs automatically without `/azp run` approval. ### Context Following up on #12022 (which migrated most on-device networking tests off live external URLs to the loopback `LocalHttpServer`/`LocalHttpsServer`) and #12058 (which handles `SslTest.HttpsShouldWork`), a few on-device tests were still reaching out to the public internet. Those requests made the tests flaky whenever the external endpoints were slow, rate-limited, or unavailable. This migrates the remaining tests to local loopback servers. ### Tests migrated | Test | Was hitting | | ---- | ----------- | | `SslTest.SslWithinTasksShouldWork` | `dotnet.microsoft.com` | | `ProxyTest.QuoteInvalidQuoteUrlsShouldWork` | `msftconnecttest.com` | | `AndroidMessageHandlerTests.ServerCertificateCustomValidationCallback_ApproveRequest` | `www.microsoft.com` | | `AndroidMessageHandlerTests.ServerCertificateCustomValidationCallback_RejectRequest` | `www.microsoft.com` | | `AndroidMessageHandlerTests.AndroidMessageHandlerSendsClientCertificate` | `corefx-net-tls.azurewebsites.net` | | `AndroidMessageHandlerIntegrationTests.GetString_Many` | `google.com` | | `HttpClientHandlerTestBase.Disposed` | `google.com` | | `WebSocketTests.TestSocketConnection` | `echo.websocket.org` (was `[Ignore]`d) | `ProxyTest` keeps its original point — an unescaped `|` in the query string (`?query&foo|bar`) — now exercised against the local `/ok` endpoint. `WebSocketTests` was previously disabled because the public echo server no longer exists; it is re-enabled against a local server. ### Test infrastructure (`LocalTestServers.cs`) - **Client certificates (mutual TLS)**: `LocalHttpsServer.Start (requestClientCertificate: true)` now requests a client certificate during the TLS handshake, and a new `/echo-client-certificate` endpoint returns the certificate the server received (base64 DER). This replaces the external `EchoClientCertificate.ashx` endpoint. - **`LocalWebSocketServer`**: a loopback WebSocket echo server that performs the upgrade handshake and echoes messages back (uses `WebSocket.CreateFromStream` after a manual `101 Switching Protocols` response). ### Notes - `HttpsShouldWork` is intentionally left to #12058. - The `http://10.255.255.1` cancellation/timeout tests deliberately use an unroutable address (not the public internet) and are unchanged. - Cosmetic external hostnames that were never actually contacted (`CancelRequestViaProxy`'s base address behind a dead proxy, and `DisallowAutoRedirect`'s redirect target) were pointed at `localhost`. The new server logic (HTTP, HTTPS, mutual-TLS echo, and WebSocket echo) was verified end-to-end against `HttpClient` and `ClientWebSocket` on desktop .NET.

CopilotAI review requested due to automatic review settings July 8, 2026 16:42

simonrozsival requested a review from jonathanpeppers as a code owner July 8, 2026 16:42

Copilotstarted reviewing on behalf of simonrozsival July 8, 2026 16:43 View session

CopilotAI reviewed Jul 8, 2026
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simonrozsivaland others added 8 commits July 8, 2026 22:14

Address networking test review feedback
aa5a91f
Bind local HTTP listeners to loopback, dispose LinkDesc HTTP resources, backdate self-signed certificates further, and assert policy errors in the HTTPS redirect callback test. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Simplify local networking test servers
551f171
Share local test server exception handling and shutdown logic, and add intent-level helpers for redirect and OK responses to remove repeated listener setup in networking tests. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

simonrozsival added flaky-tests ready-to-review This PR is ready to review/merge, I think any CI failures are just flaky (ignorable). labels Jul 9, 2026

github-actionsBot reviewed Jul 9, 2026
View reviewed changes

Comment threadtests/Mono.Android-Tests/Mono.Android-Tests/Xamarin.Android.Net/LocalTestServers.cs Outdated
Comment threadtests/MSBuildDeviceIntegration/Tests/InstallAndRunTests.cs
Comment threadtests/Mono.Android-Tests/Mono.Android-Tests/Xamarin.Android.Net/AndroidMessageHandlerTests.cs Outdated

simonrozsival enabled auto-merge (squash) July 10, 2026 07:09

jonathanpeppers approved these changes Jul 10, 2026
View reviewed changes

simonrozsival merged commit bef2665 into mainJul 10, 2026
42 checks passed

simonrozsival deleted the android-change-networking-tests branch July 10, 2026 22:17

simonrozsival mentioned this pull request Jul 13, 2026
[Flaky test] SslTest.HttpsShouldWork fails on external server errors (504 Gateway Time-out) #12057
Closed

CopilotAI mentioned this pull request Jul 13, 2026
Use a local HTTPS server in SslTest.HttpsShouldWork#12058
Merged

This was referenced Jul 14, 2026
[tests] Use local servers for remaining networking tests #12098
Closed
[tests] Use local servers for remaining networking tests #12099
Merged

github-actionsBot locked and limited conversation to collaborators Aug 10, 2026

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[tests] Use local servers for networking tests - #12022

[tests] Use local servers for networking tests#12022
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simonrozsival commented Jul 8, 2026

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