AzureDevOpsReporter: skip Assert frames by type name instead of filename (fixes #6925)

[Evangelink]

Fixes #6925. Closes #8278.

Problem

AzureDevOpsReporter.GetErrorText walks a failing test's stack frames and skips the frame if the file path ends with Assert.cs, so the reporter annotates the user's call site rather than the framework's assertion implementation:

https://github.com/microsoft/testfx/blob/main/src/Platform/Microsoft.Testing.Extensions.AzureDevOpsReport/AzureDevOpsReporter.cs#L215-L223

But Assert / CollectionAssert / StringAssert are split into partial-class files (Assert.AreEqual.cs, Assert.IComparable.cs, Assert.IsInstanceOfType.cs, CollectionAssert.Equality.cs, etc.) whose file names do not end with Assert.cs. The filter misses every one of them, so for cases like the Assert.IsInstanceOfType failure in #6925 the reporter incorrectly annotates the framework file instead of the user's test.

The filter also has the opposite problem: a user file innocently named MyAssert.cs would be wrongly skipped.

Fix

Switch the skip decision from the file name to the fully-qualified type name captured in the stack frame's code field (already parsed by StackTraceHelper.GetFrameRegex and previously unused). A frame is skipped iff its code starts with one of:

• Microsoft.VisualStudio.TestTools.UnitTesting.Assert.
• Microsoft.VisualStudio.TestTools.UnitTesting.CollectionAssert.
• Microsoft.VisualStudio.TestTools.UnitTesting.StringAssert.

This naturally covers every partial-class file (current and future), is robust against file renames/splits, and removes the MyAssert.cs false positive.

A complementary follow-up — adding [StackTraceHidden] on the same APIs once RFC 012 lands — is tracked separately in #8277 and would obviate the reporter heuristic entirely on .NET 6+. This PR is still needed for .NET Framework.

Tests

Added 5 tests to AzureDevOpsTests:

• SkipsMSTestAssertImplementationFrameInPartialClassFile — regression test for Assert.IComparable not compatible with AzDoReport extension #6925: synthetic stack with a frame in Assert.IComparable.cs followed by a user frame; asserts the user frame is reported.
• SkipsMSTestCollectionAssertImplementationFrameInPartialClassFile — same for CollectionAssert.Equality.cs.
• SkipsMSTestStringAssertImplementationFrame — same for StringAssert.cs.
• DoesNotSkipUserFrameWhoseFileNameEndsWithAssertCs — verifies the previous false positive on user files named *Assert.cs is gone (mocked IFileSystem).
• DoesNotSkipUserFrameWhoseTypeNameStartsWithAssert — verifies a user type in a non-MSTest namespace named Assert is not mistaken for the framework's Assert.

The two pre-existing tests' expected line numbers were updated because the using Moq; directive shifted the throw statements down.

All 7 tests pass on net9.0, net8.0, and net472. Full Microsoft.Testing.Extensions.UnitTests suite (124 tests) passes.

[Copilot]

Pull request overview

This PR fixes Azure DevOps reporting so MSTest assertion implementation frames are skipped by fully-qualified frame code/type prefix rather than by source filename.

Changes:

• Adds MSTest assertion type-prefix filtering in AzureDevOpsReporter.
• Adds regression tests for partial assertion files and user files/types that should not be skipped.
• Updates existing expected line numbers after new imports.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Extensions.AzureDevOpsReport/AzureDevOpsReporter.cs	Replaces filename-based Assert frame skipping with code-prefix-based assertion implementation detection.
test/UnitTests/Microsoft.Testing.Extensions.UnitTests/AzureDevOpsTests.cs	Adds synthetic stack trace tests covering MSTest assertion frame skipping and false-positive avoidance.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 1

[Evangelink]

Review Summary

This is a clean, well-scoped fix for #6925. All 21 review dimensions assessed; no blocking issues found.

Dimension	Status
1. Algorithmic Correctness	✅ Root cause fixed (type prefix vs. filename). GetStackFrameLocation guarantees code is non-null/non-empty before IsAssertionImplementationFrame is called.
2. Threading & Concurrency	✅ N/A — no shared mutable state introduced. AssertionImplementationCodePrefixes is static readonly (immutable array).
3. Security & IPC	✅ N/A
4. Public API / Binary Compat	✅ All new code is private static — no public surface added.
5. Performance	✅ foreach over 3-element static array; no allocations on the hot path.
6. Cross-TFM	✅ string.StartsWith(StringComparison.Ordinal) available on all targets.
7. IDisposable	✅ N/A
8. Defensive Coding	✅ code is validated non-empty by GetStackFrameLocation before use.
9. Localization	✅ Log messages are trace-only diagnostics, not user-facing; no .resx required.
10. Test Isolation	✅ New tests use synthetic stack traces; no shared state.
11. Assertion Quality	✅ BannedSymbols.txt bans AwesomeAssertions; tests correctly use MSTest Assert.AreEqual.
12. Flakiness	✅ GetCurrentLocation uses [CallerFilePath]/[CallerLineNumber] — deterministic at compile time.
13–21. Remaining dimensions	✅ N/A for this change.

Observations (non-blocking):

• The GetCurrentLocation() helper captures line 65 as userLine, then immediately uses it in the synthetic stack trace at line 72 and in the expected assertion output at line 80. The test is self-consistent, but note that inserting any line between GetCurrentLocation() and the stackTrace construction would silently shift the captured line without breaking the test (because both references move together). This is an accepted pattern for this kind of test, just worth knowing.
• The PR description mentions a follow-up [StackTraceHidden] initiative (#8277) that would make this heuristic unnecessary on .NET 6+. This PR remains correct and necessary for .NET Framework.

LGTM — the fix is correct, tested, and well-explained.

Generated by Expert Code Review (on open) for issue #8284 · ● 4.6M

[Evangelink]

@copilot address review comments and fix the broken test below:

test/IntegrationTests/MSTest.Acceptance.IntegrationTests/TelemetryTests.cs#L132

test/IntegrationTests/MSTest.Acceptance.IntegrationTests/TelemetryTests.cs(132,1): error : [VSTest_RunTests_Succeeds ("net462")] [net11.0] Assert.AreEqual failed. Expected:<0>. Actual:<1>. 'expected' expression: '0', 'actual' expression: 'testResult.ExitCode'. dotnet test failed:
Telemetry is: Disabled
Determining projects to restore...
Restored D:\a_work\1\s\artifacts\tmp\Debug\testsuite\gKgYA\TelemetryTests\vstest\TelemetryVSTestProject.csproj (in 484 ms).
TelemetryVSTestProject -> D:\a_work\1\s\artifacts\tmp\Debug\testsuite\gKgYA\TelemetryTests\vstest\bin\Release\net462\TelemetryVSTestProject.dll
D:\a_work\1\s.dotnet\sdk\11.0.100-preview.5.26227.104\Microsoft.Common.CurrentVersion.targets(5742,5): error MSB3491: Could not write lines to file "obj\Release\net462\TelemetryVSTestProject.csproj.FileListAbsolute.txt". Cannot create a file when that file already exists. [D:\a_work\1\s\artifacts\tmp\Debug\testsuite\gKgYA\TelemetryTests\vstest\TelemetryVSTestProject.csproj::TargetFramework=net462]

[Copilot]

@copilot address review comments and fix the broken test below:

test/IntegrationTests/MSTest.Acceptance.IntegrationTests/TelemetryTests.cs#L132
...

Addressed in e1d0f4f: the regression stack frame now uses Assert.IsLessThan from Assert.IComparable.cs, and TelemetryTests is marked [DoNotParallelize] so the shared generated VSTest asset is no longer built concurrently.

[Copilot]

Copilot's findings

• Files reviewed: 3/3 changed files
• Comments generated: 1