test: exclude crawler-e2e siblings from #[serial] env swaps via #[parallel] - #136
Merged
Mikola Lysenko (mikolalysenko) merged 1 commit intoJul 27, 2026
Merged
Conversation
…allel] Follow-up to #135, which fixed the hostile-decoy env race in the setup-matrix suites and documented the gotcha this sweep now applies repo-wide: #[serial] only excludes OTHER #[serial] tests. Nine crawler_*_e2e binaries (and cli_global_args) have #[serial] tests that swap process-global state — HOME, VIRTUAL_ENV, PATH, XDG dirs, even the process cwd (composer) — around in-process crawler calls, while dozens of unmarked sibling tests run concurrently on other threads. Unlike #135's child-spawn snapshot race (a microseconds window), the in-process variant exposes siblings for the mutator's entire body: any sibling whose crawl probes HOME-based global caches mid-swap sees the wrong universe. A helper-aware sweep of every test binary in both crates confirmed all MUTATING tests are already #[serial] (including mutation hidden inside helpers like crawler_npm_e2e's with_empty_path); the gap was solely the unmarked siblings. Fix: #[serial_test::parallel] on all 205 of them — parallel-marked tests keep running concurrently with each other but are excluded while any #[serial] test holds the lock, so suite wall-time is unchanged (binaries' runtimes identical before/after). Mechanism proven RED/GREEN with a throwaway probe pair (not committed): a #[serial] test swapping HOME for 150ms + an UNMARKED sibling asserting HOME stays stable fails 3/3 runs; marking the sibling #[parallel] passes 5/5. Same primitive as #135's proof, in-process variant. Single-test binaries with env mutation (e2e_golang_build, setup_matrix_env_guard) have no intra-process race and stay untouched. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Mikola Lysenko (mikolalysenko)
enabled auto-merge (squash)
July 27, 2026 18:25
marvinsocket
approved these changes
Jul 27, 2026
Mikola Lysenko (mikolalysenko)
deleted the
fix/crawler-e2e-parallel-guard
branch
July 27, 2026 18:35
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
What this sweep found
#135 fixed the setup-matrix decoy race and documented the gotcha:
#[serial]only excludes other#[serial]tests. Sweeping every test binary in both crates with a helper-aware analyzer (attributes each test's mutation status including mutation hidden inside helpers likecrawler_npm_e2e::with_empty_path) found the same hazard at much larger scale:#[serial]mutatorsThe serial tests swap HOME, VIRTUAL_ENV, PATH, XDG dirs, and (composer) the process cwd around in-process crawler calls. Unlike #135's child-spawn snapshot race (microseconds window), this variant exposes siblings for the mutator's entire body: any concurrently-running sibling whose crawl probes HOME-based global caches mid-swap sees the wrong universe. All mutating tests were already
#[serial]— the gap was solely their unmarked siblings.The fix
#[serial_test::parallel]on all 205 unmarked siblings. Parallel-marked tests keep running concurrently with each other but take the shared side of serial_test's lock, so they're excluded while any#[serial]test runs — suite wall-times are unchanged (verified: all ten binaries' runtimes identical before/after; 280 tests green).Blanket
#[serial](the #135 approach, right for those tiny suites) would have serialized 58-test binaries for no reason.Mechanism proven RED/GREEN
Throwaway probe pair (not committed): a
#[serial]test swapping HOME for 150ms alongside an unmarked sibling asserting HOME stays stable — fails 3/3 runs with "HOME changed mid-test"; after marking the sibling#[parallel], passes 5/5. Same primitive as #135's deterministic proof, in-process variant.Not touched
Single-test binaries with env mutation (
e2e_golang_build,setup_matrix_env_guard) — no siblings, no intra-process race.🤖 Generated with Claude Code