Use Mini dump in CrashDump child-crash test to fix macOS Debug timeout

[Evangelink]

Fixes the consistent failure of CrashDump_TesthostAndChildBothCrash_CollectsAllDumps on macOS Debug builds.

Root cause

The default crash dump type is Full. On macOS Debug builds the runtime's createdump writes a multi-GB Full dump that can take several minutes per process. A representative failure log shows the parent's dump being a 5.6 GB file written in 198857ms (~3.3 minutes):

[createdump] Writing full dump to file .../CrashDump_11912_crash.dmp
[createdump] Writing full dump to file .../CrashDump_11901_crash.dmp
[createdump] Written 5648462104 bytes (1379019 pages) to core file
[createdump] Dump successfully written in 198857ms

The test parent only waits 60s on its spawned child via child.WaitForExit(60_000). On macOS Debug:

1. Child FailFasts and createdump starts writing its (huge) dump.
2. Parent's 60s wait expires while the child's dump is still being written.
3. Parent calls child.Kill() and throws, interrupting the in-progress child dump ([createdump] Writing dump FAILED).
4. Only the parent's dump ends up on disk -> Assert.HasCount(2, dumpFiles) fails (actual: 1).

Other configurations aren't impacted because Full dumps complete far faster on Windows/Linux and on Release builds.

Fix

Pass --crashdump-type Mini in this specific test. The DbgMiniDumpType env var set by CrashDumpEnvironmentVariableProvider is inherited by the spawned child process, so both processes write small/fast Mini dumps that comfortably finish within the 60s window.

The test only validates that both dumps are collected and reported as artifacts — it doesn't care about dump contents — so Mini is semantically equivalent for this scenario.

[Copilot]

Pull request overview

This PR addresses a macOS Debug CI timeout in the Microsoft.Testing.Platform CrashDump acceptance test by switching the test scenario to request Mini dumps, avoiding multi-GB Full dump creation delays that can exceed the test’s 60s child-process wait.

Changes:

• Update CrashDump_TesthostAndChildBothCrash_CollectsAllDumps to pass --crashdump-type Mini and document the macOS Debug timeout root cause.
• Simplify a filename-collision loop in TRX artifact copying logic.
• Refactor HTML report target framework moniker selection into a single null-coalescing expression.

Show a summary per file

File	Description
test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/CrashDumpTests.cs	Requests Mini crash dumps in the child-crash scenario to prevent macOS Debug timeouts and improve test reliability.
src/Platform/Microsoft.Testing.Extensions.TrxReport/TrxReportEngine.Artifacts.cs	Simplifies the destination-exists retry loop while preserving behavior.
src/Platform/Microsoft.Testing.Extensions.HtmlReport/HtmlReportEngine.cs	Refactors GetTargetFrameworkMoniker for equivalent, more concise logic.

Copilot's findings

• Files reviewed: 3/3 changed files
• Comments generated: 0

[Evangelink]

✅ 8/8 applicable dimensions clean — no findings.

Reviewed dimensions:

1. ✅ Algorithmic Correctness — Both refactorings are semantically identical to original code
2. ✅ Threading & Concurrency — No new race conditions introduced (existing TOCTOU preserved)
3. ✅ Performance & Allocations — No hot-path changes, refactorings have no performance impact
4. ✅ Code Structure & Simplification — Excellent use of null-coalescing and while-condition extraction
5. ✅ Test Completeness & Coverage — No new code paths require coverage
6. ✅ Flakiness Patterns — Fix directly addresses root cause (timeout on macOS Debug Full dumps)
7. ✅ Naming & Conventions — Consistent with codebase style
8. ✅ Documentation Accuracy — New comment accurately explains WHY and mechanism

Skipped dimensions (not applicable): Security, Public API, Cross-TFM, Resource Management, Defensive Coding, Localization, Test Isolation, Assertion Quality, Data-Driven Coverage, Analyzer Quality, IPC Wire, Build Infrastructure, Scope Discipline.

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Summary: This PR combines a targeted test fix (switching to --crashdump-type Mini to prevent macOS Debug timeouts) with two clean refactorings (null-coalescing chain, while-condition extraction). All changes preserve exact semantics. The test fix is well-documented and addresses the root cause identified in the PR description.

Generated by Expert Code Review (on open) for issue #8483 · ● 12.6M

[Evangelink]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Merged origin/main into the branch and resolved the single conflict in CrashDumpTests.cs (both sides had the same functional change --crashdump-type Mini; only the comment text differed — kept the main branch version).