[David Fowler (davidfowl)]

Supersedes #21558. That PR's head is on a fork (davidfowl/aspire) with maintainer_can_modify=false, so it couldn't be brought up to date with main. This PR contains the same change, squashed onto current main.

Fixes #21557

Failure

On main, Infrastructure.Tests.AnalyzeCiFailureWorkflowTests.LastSuccessfulMainRunFallsBackToOlderWindow failed with Expected: 0 / Actual: 126 (run 40984409791, Infrastructure (ubuntu-latest)).

Denominator: 1 failure in 115 attempt-1 Infrastructure (ubuntu-latest) jobs in the last ~48h of ci.yml runs (104 success, 3 failure, 8 cancelled). The other two failures were unrelated, PR-specific breaks.

Root cause

This is the ETXTBSY ("Text file busy") race that #21448 fixes for Aspire.Acquisition.Tests (#18732). This PR fixes it in tests/Infrastructure.Tests, which #21448 doesn't touch.

1. Several tests write a stub executable (gh, actionlint, curl, dotnet.sh) from the test host with File.WriteAllText[Async], then chmod it and run a script that execs it.
2. xUnit runs test classes in parallel, so other tests in the same host keep starting processes.
3. A child forked while the host has the stub open for writing inherits that descriptor until it calls exec.
4. Linux refuses to exec a file that any process has open for writing, returning ETXTBSY. bash reports that as exit 126.

Writing to a temp file and renaming it doesn't help, because the inherited descriptor still refers to the same inode.

Fix

• New ExecutableFile.WriteAsync/Write test helper. On Unix it writes the contents (from stdin) and sets the mode inside a short-lived /bin/sh -c 'cat > "$1" && chmod "$2" "$1"' child, so the test host never holds a writable descriptor that another fork could inherit. On Windows it is a plain File.WriteAllTextAsync.
• Every Infrastructure.Tests call site that execs a freshly written stub now uses the helper:
  • AnalyzeCiFailureWorkflowTests
  • LintHandwrittenWorkflowsScriptTests
  • NixCliPackageTests
  • TemplateManifestGenerationTests
  • ExtensionReleaseWorkflowTests (the separate chmod +x step is removed)
• BuildWarningPolicyTests is unchanged because it runs bash build.sh rather than exec'ing the file.
• No assertions are changed, and no sleeps or retries are added.

Regression test

ExecutableFileTests.WrittenExecutableCanBeExecutedImmediatelyWhileOtherThreadsStartProcesses (Unix only):

• Four threads continuously fork /bin/sh -c "exit 0".
• Meanwhile, 1000 stubs are written with the helper and exec'd immediately.
• The test asserts that no launch fails and that each stub returns its expected exit code.

WritesContentsAndExecutableMode checks that the contents and mode round-trip.

Helper's Unix path	Test runs failed	Launches failed
Before: in-process File.WriteAllTextAsync + File.SetUnixFileMode	20 / 20	561 / 20,000 (18–35 per run, all Text file busy)
After: this PR	0 / 20	0 / 20,000

Change since #21558

main moved AnalyzeCiFailureWorkflowTests.cs into the new tests/AnalyzeCiFailure.Tests project. The helper call moved with it, so ExecutableFile.cs is now linked into that project (<Compile Include="../Infrastructure.Tests/ExecutableFile.cs" Link="shared/ExecutableFile.cs" />). This uses the same pattern the project already uses for RepoRoot.cs and CommandResult.cs. Without the link the project fails to build with CS0103.

Confidence

• Behavior and regression coverage: High. ExecutableFileTests reproduces the race: the old write path failed in 20 of 20 runs, and the new helper failed in 0 of 20. No assertions changed in the converted tests.
• Tests and pipelines run: Ran locally on Linux against this commit:
  • AnalyzeCiFailure.Tests: 1162 of 1163 passed. The one failure, AnalyzerBuildsFromRealSparseCheckoutWithoutHostileParentImports, comes from NuGet's vulnerability check (audit) being unable to reach nuget.org from the local machine (NU1900/NU1905), not from this change.
  • Infrastructure.Tests classes this PR touches, all passing: ExecutableFile 2/2, NixCliPackage 3/3, TemplateManifestGeneration 7/7, ExtensionReleaseWorkflow 9/9, LintHandwrittenWorkflowsScript 3/3.
  • CI is pending.
• Build artifacts: Not affected. Only test code and a test .csproj change; no product or packaging changes.
• E2E: Not applicable. This is test-infrastructure only.

How we stop this recurring: New tests that exec a freshly written stub should write it with ExecutableFile.WriteAsync instead of File.WriteAllText followed by chmod. The regression test guards the helper itself.

🤖 Posted by AspireAgent (AI Agent)

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 21749

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/microsoft/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 21749"

[github-actions]

Tests selector

2 / 101 PR test projects · 0 PR jobs, from 8 changed files.

Selected PR test projects (2 / 101)

AnalyzeCiFailure.Tests, Infrastructure.Tests

Selected PR jobs (0)

none

---

How these were chosen — grouped by what changed

🧪 tests/AnalyzeCiFailure.Tests/AnalyzeCiFailure.Tests.csproj (changed test)
→ 1 directly: AnalyzeCiFailure.Tests

🧪 tests/AnalyzeCiFailure.Tests/AnalyzeCiFailureWorkflowTests.cs (changed test)
→ 1 directly: AnalyzeCiFailure.Tests

🧪 tests/Infrastructure.Tests/ExecutableFile.cs (changed test)
→ 1 directly: Infrastructure.Tests

🧪 tests/Infrastructure.Tests/ExecutableFileTests.cs (changed test)
→ 1 directly: Infrastructure.Tests

🧪 tests/Infrastructure.Tests/Pipelines/NixCliPackageTests.cs (changed test)
→ 1 directly: Infrastructure.Tests

🧪 tests/Infrastructure.Tests/TemplateManifest/TemplateManifestGenerationTests.cs (changed test)
→ 1 directly: Infrastructure.Tests

🧪 tests/Infrastructure.Tests/WorkflowScripts/ExtensionReleaseWorkflowTests.cs (changed test)
→ 1 directly: Infrastructure.Tests

🧪 tests/Infrastructure.Tests/WorkflowScripts/LintHandwrittenWorkflowsScriptTests.cs (changed test)
→ 1 directly: Infrastructure.Tests

Job reasons

none

---

Selection computed for commit ec3f028.

[Copilot]

🟢 Approval recommended

No active review issues remain for the test-infrastructure changes addressing the executable-writing race.

No open issues 🎉

What changed in this PR

Addresses the Unix “Text file busy” race in test-created executables by moving file writing and permission setting into a child process. The change is limited to test infrastructure; product and packaging behavior are unchanged.

Changes:

• Adds a shared executable-writing helper with a plain file-write path on Windows.
• Migrates fake executable creation across infrastructure and CI-analysis tests, linking the helper into the separate analysis test project.
• Adds concurrent-process regression coverage and content/permission round-trip checks.

File	Description
tests/​Infrastructure.Tests/​WorkflowScripts/​LintHandwrittenWorkflowsScriptTests.cs	Uses the helper to create the fake actionlint executable.
tests/​Infrastructure.Tests/​WorkflowScripts/​ExtensionReleaseWorkflowTests.cs	Migrates fake gh creation and removes the separate chmod runner.
tests/​Infrastructure.Tests/​TemplateManifest/​TemplateManifestGenerationTests.cs	Uses the synchronous helper for the Unix dotnet.sh stub.
tests/​Infrastructure.Tests/​Pipelines/​NixCliPackageTests.cs	Migrates both fake curl executables while preserving permissions.
tests/​Infrastructure.Tests/​ExecutableFileTests.cs	Adds concurrent-launch regression and content/permission tests.
tests/​Infrastructure.Tests/​ExecutableFile.cs	Adds shared synchronous and asynchronous executable-writing helpers.
tests/​AnalyzeCiFailure.Tests/​AnalyzeCiFailureWorkflowTests.cs	Routes fake executable creation through the shared helper.
tests/​AnalyzeCiFailure.Tests/​AnalyzeCiFailure.Tests.csproj	Links the helper into the CI-analysis test project.

_{Review effort: Balanced}

[github-actions]

Retrying the failed CI jobs for this pull request from the CI run attempt. The rerun is being tracked in the rerun attempt.

[Jose Perez Rodriguez (joperezr)]

Moving Unix executable-fixture writing into a child process addresses the writable-descriptor inheritance race without changing the fake scripts or their expected results. Existing argument, exit-code, and output assertions remain, and the added regression still requires the intended nonzero stub exit. No product behavior or failure expectation is relaxed.

[aspire-repo-bot]

✅ No documentation update needed.

docs_optional → test_only (proven false positive). Triggered signal: pr_body_has_security_marker — evidence is PR-body prose about NuGet's vulnerability audit being unable to reach nuget.org locally, not a security change. All 8 changed files match tests/** (AnalyzeCiFailure.Tests, Infrastructure.Tests); only_test_or_build_changes is true. No user-facing change.