⚡ perf(test): parallelize test suite with pytest-xdist - #3035
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The test suite ran serially at ~74s. Adding pytest-xdist with `-n auto --dist loadfile` distributes tests across CPU cores while keeping same-file tests together for efficient session-fixture reuse. The existing coverage infrastructure (coverage-enable-subprocess, COVERAGE_PROCESS_START, coverage combine) already handles subprocess coverage, so no additional wiring was needed. Also skip pip seeding in test_create_long_path since it only validates long path support, and reduce the per-test timeout from 600s to 120s since the slowest test takes ~6s. Wall-clock time drops from ~74s to ~26s.
gaborbernat
marked this pull request as ready for review
February 15, 2026 16:24
gaborbernat
enabled auto-merge (squash)
February 15, 2026 16:24
This was referenced Mar 12, 2026
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The test suite runs all 420 tests serially, taking ~74s on a modern machine. For a project where CI runs across many Python versions, this adds up quickly. 🕐
This adds
pytest-xdistand configures tox to run tests with-n auto --dist loadfile. Theautoflag scales workers to available CPU cores, whileloadfilekeeps tests from the same file on the same worker so session-scoped fixtures (likeactivation_pythonwhich creates a shared venv) aren't needlessly recreated. The existing coverage infrastructure —coverage-enable-subprocess,COVERAGE_PROCESS_START, andcoverage combine— already handles subprocess coverage collection, so no additional wiring was needed.Also removes unnecessary pip seeding from
test_create_long_path(it only validates long path support, not pip) and reduces the per-test timeout from 600s to 120s since the slowest test takes ~6s. ⚡ Wall-clock time drops from ~74s to ~26s with no change in test results or coverage.