Enabled isolate: false for the ghost/core unit suite

[9larsons]

The ghost/core unit suite ran under vitest's default isolate: true — a fresh module registry per test file, cold-importing Ghost's heavy server modules ~550 times per run. It now runs under isolate: false (one shared registry per worker, the model mocha always used): ~73s → ~7s locally.

How

vitest.config.ts is split into two projects:

• unit — the 546-file bulk, isolate: false.
• unit-isolated — 4 files that still fail intermittently under a shared registry, kept on isolate: true until their root causes are fixed: create-migration, scheduling-default, public-config/config, taxonomy-router. The quarantine list is short on purpose — each entry is a known bug to fix, not a permanent home.

Supporting changes for the shared registry:

• vitest-setup.ts's afterAll no longer destroys the knex pool per file — under one shared pool per worker that would break every file scheduled after it. It now drains in-flight queries and leaves the pool for the worker to tear down.
• vitest-global-setup.ts removes the per-worker session sqlite files once per run (previously done per-file).
• cache-invalidation.test.js is un-skipped — it was skipped specifically pending this change; warm requires keep it well under the timeout.
• Three snapshot files pick up vitest's current header line (Jest→Vitest); isolate: false rewrites them on load, content unchanged.

Verification

The isolate: false bulk project was stress-run 82 times locally (full suite, ~546 files) — 81 clean, 1 lone unrelated flake, well within the existing vitest retry: 2 + CI step-retry. Full suite (both projects) green at 550/550.

🤖 Generated with Claude Code

[coderabbitai]

Walkthrough

This PR restructures Ghost core's Vitest unit test execution into two separate projects: unit (shared module state, isolate: false) and unit-isolated (isolated, isolate: true). An isolatedFiles allowlist routes quarantined tests to the isolated runner. The setup logic now generates a per-worker sessionId and removes conditional sqlite/mysql cleanup flags. The afterAll hook now best-effort waits up to 5 seconds for the shared knex pool to drain instead of destroying it. A new global teardown removes leftover SQLite test database files from /tmp. The previously skipped cache-invalidation header assertion test is enabled.

Possibly related PRs

• TryGhost/Ghost#28030: Modifies Vitest unit-test wiring and configuration for ghost/core, related to the project/isolation refactor.
• TryGhost/Ghost#28012: Changes to knex teardown/cleanup in vitest-setup.ts, closely related to the afterAll cleanup adjustments.
• TryGhost/Ghost#28049: Previously skipped the same cache-invalidation test that this PR re-enables.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Enabled isolate: false for the ghost/core unit suite' directly and clearly describes the main performance optimization change—switching the unit test suite from isolate: true to isolate: false.
Description check	✅ Passed	The description is comprehensive and directly related to the changeset, explaining the rationale (73s → 7s performance improvement), implementation approach (two-project split), supporting changes, and verification results.
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.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch perf/unit-tests-isolate-false

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Actionable comments posted: 1

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 33e9a606-cd73-4301-8476-7103ce1aed9b

📥 Commits

Reviewing files that changed from the base of the PR and between 47e19e2 and 1fef525.

📒 Files selected for processing (4)

• ghost/core/test/unit/api/cache-invalidation.test.js
• ghost/core/test/utils/vitest-global-setup.ts
• ghost/core/test/utils/vitest-setup.ts
• ghost/core/vitest.config.ts