Add cooperative slow-test diagnostics for browser

[Evangelink]

Browser and WASI test runs cannot use the HangDump extension because it depends on process APIs and named pipes. This adds a lightweight diagnostic path that identifies active tests which remain running without relying on unsupported browser threading or process facilities.

• Track active tests by UID in the shared simplified Browser/WASI output device.
• Emit durable [slow] still running after ... lines using the existing MTP_PROGRESS_SLOW_TEST_SECONDS setting (0 disables reporting).
• Share one exponential threshold/backoff state across Browser/WASI diagnostics, terminal heartbeat output, and the Azure DevOps/GitHub Actions slow-test reporter base.
• Skip obsolete catch-up thresholds after delayed polls while reporting the actual elapsed duration.
• Keep test starts silent so immediate per-test progress remains a separate concern.
• Reuse the localized slow-test message without adding public API.
• Document that cooperative reporting diagnoses asynchronous hangs, but cannot run while a synchronous test blocks the sole WebAssembly thread.

Validation includes focused platform and extension unit tests, warning-free multi-target builds for the platform and both linked-source CI extensions, and publishing/running BrowserPlayground under Node. MSBuild validation was captured with binary logs.

Related to #2196, specifically #2196 (comment).

[Copilot]

Pull request overview

Adds cooperative slow-test diagnostics for browser/WASI environments.

Changes:

• Tracks active tests and reports slow tests with exponential backoff.
• Shares terminal progress configuration and localized messaging.
• Adds focused tests, API tracking, and browser documentation.

Show a summary per file

File	Description
SimplifiedConsoleOutputDeviceTests.cs	Tests tracking and reporter lifecycle.
ActiveTestTrackerTests.cs	Tests thresholds, backoff, and UID handling.
TerminalOutputDevice.Initialization.cs	Uses shared progress configuration.
TerminalOutputDevice.cs	Removes relocated constants.
SimplifiedConsoleOutputDeviceBase.cs	Integrates tracking and cooperative reporting.
ProgressReportingConfiguration.cs	Centralizes environment-based thresholds.
ActiveTestTracker.cs	Implements active-test tracking and backoff.
InternalAPI.Unshipped.txt	Tracks new internal APIs.
BrowserPlayground/README.md	Documents slow-test diagnostics.

Review details

• Files reviewed: 9/9 changed files
• Comments generated: 2
• Review effort level: Medium

[github-actions]

Note

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Summary

Well-structured PR that adds cooperative slow-test diagnostics to the simplified console output device, enabling browser-wasm scenarios where timers/threads are unavailable. The design is sound: async polling with exponential backoff, clean separation of tracker logic, and good test coverage.

Findings

Severity	Finding
⚠️ Medium	Potential race in OnTestSessionFinishingAsync — fields _slowTestReporterCancellationTokenSource and _slowTestReporterTask are read/nulled without atomicity guarantees. Use Interlocked.Exchange.
💡 Low	GetDueDiagnostics() allocates on every poll even when no tests are due (empty list → array). Consider early-return with cached empty array or avoid the list allocation.
💡 Low	The reporter won't restart if a second test session starts after the first finishes (flag not reset). Probably fine for current usage but worth a comment.

Verdict

The race condition in session teardown is the only item worth addressing before merge — the rest are suggestions. Overall this is clean, well-tested code with good documentation.

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Review details

• Files reviewed: 13/13 changed files
• Comments generated: 3
• Review effort level: Medium

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Review details

• Files reviewed: 20/20 changed files
• Comments generated: 1
• Review effort level: Medium

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Review details

Comments suppressed due to low confidence (2)

src/Adapter/MSTest.TestAdapter/TestingPlatformAdapter/MSTestTestNodeConverter.cs:61

• This completion marker is still ignored by other active-test consumers. HangDumpActivityIndicator.cs:132-146 and CrashDumpSequenceLogger.cs:166-181 only end tests for a TestNodeStateProperty, while VideoRecorderSessionHandler.DataConsumer.cs:22-58 leaves the UID in _inFlight when state is null. A programmatically dropped test will therefore remain “running” in hang/crash diagnostics, and video segment pruning can remain pinned to its start time. Handle this marker as an outcome-less completion in those consumers as well, with regression coverage.

        testNode.Properties.Add(TestNodeExecutionCompletedProperty.CachedInstance);

src/Platform/Microsoft.Testing.Platform/OutputDevice/SimplifiedConsoleOutputDeviceBase.cs:516

• Revalidating only by UID has an ABA race. While this method waits for the output lock, the due test can complete and a new execution with the same UID can start; the new entry makes IsActive return true, so the stale diagnostic (old name/elapsed time) is emitted even though the replacement has not reached the threshold. Same-UID restart is explicitly supported by ConsumeAsync_EmptyResult_AllowsSameTestToReportProgressAgain. Carry a tracker generation/entry identity in the diagnostic and verify that exact entry before logging.

                if (!_activeTestTracker.IsActive(diagnostic.Uid))

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

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Review details

• Files reviewed: 26/26 changed files
• Comments generated: 1
• Review effort level: Medium

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Review details

Comments suppressed due to low confidence (1)

src/Adapter/MSTest.TestAdapter/TestingPlatformAdapter/MtpTestResultRecorder.cs:48

• This neutral completion update is not preserved by either server transport. In --server dotnettestcli, TerminalOutputDevice returns before handling it and DotnetTestDataConsumer.GetTestNodeDetails drops every node without a TestNodeStateProperty, so the SDK receives the preceding in-progress message but no message that clears it. The JSON-RPC path forwards the update, but both serializers classify state-less nodes as node-type: group, turning the action node into a group update on the wire. Please add an explicit transport representation/filter for outcome-less completion and cover both server paths; otherwise programmatically dropped tests remain active or corrupt the remote node shape.

    public Task RecordEmptyResultAsync(UnitTestElement testElement)
        => PublishAsync(MSTestTestNodeConverter.ToEmptyResultTestNode(testElement, _isTrxEnabled));

• Files reviewed: 33/33 changed files
• Comments generated: 0 new
• Review effort level: Medium

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Review details

• Files reviewed: 33/33 changed files
• Comments generated: 1
• Review effort level: Medium

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Review details

• Files reviewed: 36/36 changed files
• Comments generated: 1
• Review effort level: Medium

[github-actions]

🧪 Test quality grade — PR #10128

Grade	Test	Mutation	Notes	How to improve
B (80–89)	new AzureDevOpsSlowTestReporterTests. ConsumeAsync_ ExecutionCompleted_ StopsTrackingAsync	2/3 killed	Single assertion verifies no slow-test output; a mutation that skips InProgress tracking would survive.	Add a prior ScanOnceAsync call after InProgress to confirm the test was being tracked before ExecutionCompleted stops it.
A (90–100)	mod MtpTestResultRecorderTests. MtpTestResultRecorder_ RecordEmptyResult_ PublishesExecutionCompletedNode	3/3 killed	Asserts both presence of TestNodeExecutionCompletedProperty and absence of TestNodeStateProperty, covering the key contract.	—
A (90–100)	new CrashDumpSequenceLoggerTests. ConsumeAsync_ ExecutionCompleted_ WritesEndedRecord	3/3 killed	Verifies file content with start/end predicates; timestamp is correctly left unchecked (non-deterministic).	—

_{This advisory comment was generated automatically. Grades are heuristic and informational — they do not block merging. Re-run with /grade-tests.}

🤖 Automated content by GitHub Copilot. Generated by the Grade Tests on PR (on open / sync) workflow. · sonnet46 56.6 AIC · ⌖ 4.23 AIC · ⊞ 10.3K · [◷]( · ◷)

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Review details

• Files reviewed: 42/42 changed files
• Comments generated: 0 new
• Review effort level: Medium