test: fix temp-fixture directory collisions in parser test suites

[adamgell]

Problem

src-tauri/tests/cmtlog_parser.rs had a race that made the whole test binary intermittently fail:

---- header_entry_parsed_correctly stdout ----
thread 'header_entry_parsed_correctly' panicked at src-tauri/tests/cmtlog_parser.rs:135:30:
index out of bounds: the len is 0 but the index is 0
test result: FAILED. 8 passed; 1 failed

TempLogFixture::new derived its temp directory name from SystemTime::now().duration_since(UNIX_EPOCH).as_nanos(). as_nanos() does not guarantee distinct values between calls; macOS clock granularity is coarser than a nanosecond, so two fixtures constructed within the same observed tick got the same directory path.

Each fixture also implemented Drop as fs::remove_dir_all(&self.dir). The test harness runs a binary's tests on parallel threads, so whichever test finished first deleted the other test's fixture file. The victim then read an empty/missing file, parsed zero entries, and panicked on result.entries[0].

This reproduced roughly 1 run in 5 of the full cargo test --locked suite on an M-series Mac. Running the single binary alone rarely reproduced it, since there is far less scheduling pressure.

Scope

The same time-derived pattern had been copied into four places, all with the same remove_dir_all destructor:

File	Prefix
src-tauri/tests/cmtlog_parser.rs	cmtrace-open-cmtlog-test-
src-tauri/tests/parser_regression_corpus.rs	cmtrace-open-parser-regression-
src-tauri/tests/parser_expanded_corpus.rs	cmtrace-open-expanded-
src-tauri/tests/common/mod.rs (TempBenchFile)	cmtrace-open-bench-

tests/common/mod.rs is also pulled into benches/intune_pipeline.rs via #[path = "../tests/common/mod.rs"], so the benchmark fixture carried the defect too.

Fix

tempfile = "3" was already in [dev-dependencies], so each fixture now holds a TempDir built with TempDir::with_prefix(...). That takes uniqueness from the OS (random suffix plus O_EXCL retry) rather than from the clock, and TempDir's own Drop handles cleanup, so all four hand-rolled Drop impls are removed. Net 34 lines deleted.

The fixture structs keep the directory alive via a _dir: TempDir field; dropping it early would delete the directory out from under the still-live path.

Verification

• 12 consecutive cargo test --locked runs, 785 tests each, zero failures
• One cargo test --locked --all-features run, adding the feature-gated binaries including esp_diagnostics_sources, zero failures
• cargo clippy --all-targets -- -D warnings clean
• 5 further full suites after a collateral revert (below): still zero failures

Note

cargo fmt reformatted 13 unrelated files on this branch that were already non-conformant (12 under src-tauri/src/, plus tests/esp_diagnostics_sources.rs). That collateral was reverted to keep this diff minimal. There is no cargo fmt --check gate in .github/workflows/, so the drift is pre-existing and unenforced; worth cleaning up separately if desired.

Found while working #395, but entirely unrelated to it, so it lands on its own.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Tests
  • Improved test isolation by using dedicated temporary directories.
  • Automated cleanup of temporary test data to reduce leftover files and improve reliability.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: a02dc6ee-6345-425a-88ed-0b46cfd4b532

📥 Commits

Reviewing files that changed from the base of the PR and between 03e55c3 and 5e4527c.

📒 Files selected for processing (4)

• src-tauri/tests/cmtlog_parser.rs
• src-tauri/tests/common/mod.rs
• src-tauri/tests/parser_expanded_corpus.rs
• src-tauri/tests/parser_regression_corpus.rs

---

📝 Walkthrough

Walkthrough

Test fixtures across the parser test suites now use tempfile::TempDir for isolated directory creation and automatic cleanup. Timestamp-based paths, manual directory removal, and custom Drop implementations were removed.

Changes

Temporary fixture cleanup

Layer / File(s)	Summary
Migrate test fixtures to TempDir src-tauri/tests/cmtlog_parser.rs, src-tauri/tests/common/mod.rs, src-tauri/tests/parser_expanded_corpus.rs, src-tauri/tests/parser_regression_corpus.rs	Fixtures create prefixed TempDir instances, retain their handles, and derive file paths from them.
Remove manual cleanup src-tauri/tests/cmtlog_parser.rs, src-tauri/tests/parser_regression_corpus.rs	Custom Drop implementations and recursive directory removal were deleted.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the fix for temporary fixture directory collisions in parser test suites.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Fix failing CI checks

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

---

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[Copilot]

Pull request overview

This PR fixes intermittent, parallel-test fixture collisions in the src-tauri parser test suites by switching from time-derived temp directory names (which can collide on coarse-granularity clocks) to tempfile::TempDir-managed unique directories. This stabilizes integration tests that create and clean up temp fixtures while the Rust test harness runs tests concurrently.

Changes:

• Replaced SystemTime::now().as_nanos()-derived temp directory naming with TempDir::with_prefix(...) across affected test/bench fixtures.
• Removed custom Drop implementations that manually remove_dir_all’d shared temp paths, relying on TempDir’s cleanup instead.
• Updated fixture structs to retain the TempDir via a _dir: TempDir field so the directory outlives any paths derived from it.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src-tauri/tests/cmtlog_parser.rs	Uses TempDir to create per-test unique fixture directories; removes manual cleanup Drop.
src-tauri/tests/parser_regression_corpus.rs	Uses TempDir for unique temp fixtures to avoid cross-test directory collisions.
src-tauri/tests/parser_expanded_corpus.rs	Migrates temp fixture directory creation to TempDir and removes manual directory deletion.
src-tauri/tests/common/mod.rs	Updates shared bench/test fixture helper to use TempDir for safe unique directories and cleanup.