Add target framework to default TRX file name

[Jakub Jareš (nohwnd)]

When running multi-TFM tests, TRX files were overwritten because the default filename did not include the target framework. The TFM was already appended when using the LogFilePrefix parameter, but not for the default auto-generated filename.

This change appends the framework short name (e.g. net10.0) to the default TRX filename, matching the existing behavior for LogFilePrefix.

Before: username_MACHINE_2026-03-24_07_51_08.trx
After: username_MACHINE_2026-03-24_07_51_08_net10.0.trx

Closes #15506

[Copilot]

Pull request overview

Prevents TRX files from being overwritten in multi-target (multi-TFM) test runs by including the target framework in the default, auto-generated TRX filename (matching the existing LogFilePrefix behavior).

Changes:

• Append target framework short name (e.g., net10.0) to the default TRX file base name when TargetFramework is available.
• Add unit tests to validate default TRX naming with and without a target framework.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
test/Microsoft.TestPlatform.Extensions.TrxLogger.UnitTests/TrxLoggerTests.cs	Adds coverage ensuring default TRX filenames include TFM (when provided) and still work without it.
src/Microsoft.TestPlatform.Extensions.TrxLogger/TrxLogger.cs	Updates default TRX filename generation to append the framework short name when present.

[Amaury Levé (Evangelink)]

LGTM. Small, well-scoped change that correctly aligns the default TRX filename behavior with the existing LogFilePrefix path. The consistency table tells the story:

Path	TFM before PR	TFM after PR
LogFileName (explicit)	n/a	n/a
LogFilePrefix	✅	✅
Default (auto-generated)	❌	✅

Left a couple of optional nits (whitespace guard, fallback test) but nothing blocking.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

test/Microsoft.TestPlatform.Extensions.TrxLogger.UnitTests/TrxLoggerTests.cs:3

• Assert.Contains / Assert.EndsWith are not MSTest string assertions in many MSTest versions (and can even bind to the wrong overloads, e.g., treating the string as IEnumerable). To make these tests robust and unambiguous, use StringAssert.Contains(...) / StringAssert.EndsWith(...) (or Assert.IsTrue(fileName.Contains(...)) / Assert.IsTrue(fileName.EndsWith(...))) with the same messages.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[Copilot]

New behavior uses the raw TargetFramework string when parsing fails, but there’s no test coverage for raw values containing characters that are invalid in filenames or path separators (e.g., Some/Framework, ..\\x, net10.0:custom). Adding a unit test for sanitization (or expected failure behavior) would prevent regressions and validate safe filename handling.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

This test is intended to verify behavior when no framework is available, but it doesn’t explicitly clear DefaultLoggerParameterNames.TargetFramework. If _parameters is reused across tests (or pre-populated in setup), the test may not actually exercise the no-framework path. Consider removing DefaultLoggerParameterNames.TargetFramework (and/or asserting the filename does NOT contain a _<tfm> suffix) to make the scenario deterministic.

Suggested change

	_parameters.Remove(TrxLoggerConstants.LogFileNameKey);
	_parameters.Remove(TrxLoggerConstants.LogFileNameKey);
	_parameters.Remove(DefaultLoggerParameterNames.TargetFramework);