Handle report merge directory creation failures

[Amaury Levé (Evangelink)]

Trx and Ctrf artifact post-processors could throw when their fixed merged output directory could not be created, allowing a filesystem condition during post-processing to fail the test run contrary to RFC 018.

This change handles IOException and UnauthorizedAccessException consistently with the HTML and JUnit processors by returning no merged artifact and preserving the inputs. It adds portable file-collision coverage plus dangling directory symlink regressions for both processors.

The targeted project builds for net462, net472, net8.0, and net9.0, and all 21 Trx/Ctrf processor tests pass on net9.0.

Fixes #10733

[github-actions]

🧵 Parallel-safety audit — PR #10734

Parallelization — assemblies touched by this PR:

Test assembly	Scope	Workers	Analyzer coverage
Microsoft.Testing.Extensions.UnitTests	MethodLevel ([assembly: Parallelize(Scope = ExecutionScope.MethodLevel, Workers = 0)] in Program.cs)	CPU count	coverable once the parallel-safety analyzers ship (attribute-based opt-in)

MethodLevel scope means every test method is its own chunk and both same-class and cross-class conflicts are live — the strictest scope to audit against.

Findings: A (global-state) 0 · B (paths) 0 · C (declaration) 0 · D (over-serialization) 0 — by severity: Critical 0 · High 0 · Warning 0 · Info 0.

This PR adds four new [TestMethod]s (two each to CtrfArtifactPostProcessorTests.cs and the mirrored TrxArtifactPostProcessorTests.cs) covering "merged path is a file" and "merged directory is a dangling symlink" scenarios, plus the corresponding production try/catch around Directory.CreateDirectory in CtrfArtifactPostProcessor.cs / TrxArtifactPostProcessor.cs.

Each new test:

• Roots all I/O under a fresh CreateTemporaryDirectory() (Path.Combine(Path.GetTempPath(), $"...-{Guid.NewGuid():N}")), so no path is shared with any other test — no collision possible even under MethodLevel.
• Cleans up via Directory.Delete(root, recursive: true) in a finally block.
• Mutates no environment variable, current directory, console state, culture, or static/shared field — only files inside its own unique temp root.
• Declares no [ResourceLock] / [DoNotParallelize], and none is needed: the resource (a per-test GUID directory) is owned, not shared, so there's nothing to coordinate.
• The production code under test (Directory.CreateDirectory, IsReparsePoint, symlink creation/removal) only touches the path it's handed — no process-global read beyond the per-test root.

No under-declaration, no near-miss keys, no over-serialization, and no config/opt-in change in this PR. Nothing to flag for parallel-safety.

_{Advisory only — heuristic, non-blocking. Re-run with /parallel-audit. This audit answers "is it parallel-safe?"; for testability, smells, or flakiness see the detect-static-dependencies / test-smell-detection / test-anti-patterns analyses.}

🤖 Automated content by GitHub Copilot. Generated by the Parallel-safety audit on PR (on open / sync) workflow. · auto · 59.3 AIC · ⌖ 1.58 AIC · ⊞ 24.8K · [◷]( · ◷)

[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: The PR correctly hardens Directory.CreateDirectory against IOException and UnauthorizedAccessException (e.g., when the "merged" path already exists as a file or as a dangling symlink). Returning null aligns with the existing never-fail-the-run invariant already documented in the TRX post-processor. Tests cover both the "path is a file" case (cross-platform) and the "dangling reparse point" case (NETCOREAPP-only, with appropriate Assert.Inconclusive guard). No threading, API surface, security, or flakiness concerns.

[github-actions]

🧪 Expert test review — PR #10734

Grade	Test	Mutation	Notes	How to improve
A (90–100)	new CtrfArtifactPostProcessorTests. ProcessAsync_ WhenMergedPathIsAFile_ DoesNotMerge	2/2 killed	Exercises the new try/catch around Directory.CreateDirectory; asserts null output and untouched inputs.	—
A (90–100)	new CtrfArtifactPostProcessorTests. ProcessAsync_ WhenMergedDirectoryIsADanglingReparsePoint_ DoesNotMerge	2/2 killed	Covers the dangling-symlink path and additionally asserts the missing target is never materialized.	—
A (90–100)	new TrxArtifactPostProcessorTests. ProcessAsync_ WhenMergedPathIsAFile_ DoesNotMerge	2/2 killed	Mirrors the Ctrf case for the Trx processor's identical try/catch guard; good input-preservation checks.	—
A (90–100)	new TrxArtifactPostProcessorTests. ProcessAsync_ WhenMergedDirectoryIsADanglingReparsePoint_ DoesNotMerge	2/2 killed	Same dangling-symlink coverage as the Ctrf counterpart; verifies inputs untouched and target not created.	—

All four new tests properly wrap their Directory.CreateSymbolicLink calls in a
platform-tolerant try/catch with Assert.Inconclusive fallback, use isolated
per-test temp directories cleaned up in finally, and assert both the negative
outcome (null result) and that input artifacts are left untouched — matching
the "never-fail-the-run" invariant the production change protects. No
correctness, isolation, or maintainability issues found; no inline suggestions
were warranted.

_{This advisory comment was generated automatically. Grades are heuristic
and informational — they do not block merging. Suggestions on the Files
changed tab can be applied with one click. Re-run with
/review-tests.}

🤖 Automated content by GitHub Copilot. Generated by the Test Reviewer on PR (on open / sync) workflow. · auto · 66.7 AIC · ⌖ 0.955 AIC · ⊞ 16.9K · [◷]( · ◷)

[Copilot]

Pull request overview

Prevents TRX and CTRF report merging failures from failing test runs.

Changes:

• Handles directory creation failures by returning no merged artifact.
• Adds file-collision and dangling-symlink regression tests.

Show a summary per file

File	Description
TrxArtifactPostProcessor.cs	Handles expected filesystem exceptions.
CtrfArtifactPostProcessor.cs	Handles expected filesystem exceptions.
TrxArtifactPostProcessorTests.cs	Adds collision and dangling-link coverage.
CtrfArtifactPostProcessorTests.cs	Adds collision and dangling-link coverage.

Review details

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• Files reviewed: 4/4 changed files
• Comments generated: 0
• Review effort level: Balanced