Bump Vitest to v4

[RobinMalfait]

This PR bumps Vitest from v2 to v4. As far as I know we don't use any Vitest specific features in our tests, but had to upgrade the vitest.workspace.ts file to a vitest.config.ts file instead.

The only features we use are the typical describe, it, test, and expect functions.

The only other part we use is vi.spyOn and vi.fn but those didn't change in API either.

The test shards were removed to prevent errors. Not all suites have enough files / tests to be broken up into 3 parts so Vitest now errors when that happens.

Test plan

1. All tests should pass in CI.
2. All integration tests should pass in CI.

Enabling [ci-all], to make sure all tests pass on all platforms.

[thecrypticace]

The Vitest tests timeout because of the repeated design system reloading + canonicalization cache prefilling.

[coderabbitai]

Walkthrough

This pull request consolidates test infrastructure and optimization across the codebase. The integration test CI workflow is simplified from three sharded steps to one combined test per integration. The Vitest dependency is upgraded from ^2.0.5 to ^4.0.3. A new vitest.config.ts file is introduced to configure test discovery and exclusions, while the vitest.workspace.ts export is removed. Throughout multiple test files, explicit timeout configurations (ranging from 10,000 to 25,000 ms) are added, and performance-oriented CSS theme blocks are injected into test setups. The TestConfig interface gains optional timeout support for per-test timeout overrides.

Pre-merge checks

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: upgrading Vitest from v2 to v4, which is directly reflected in the package.json bump and vitest configuration migration.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description check	✅ Passed	The PR description accurately describes the changeset: Vitest upgrade from v2 to v4, migration from vitest.workspace.ts to vitest.config.ts, removal of test shards, and use of standard test APIs without breaking changes.

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[coderabbitai]

Actionable comments posted: 2

📜 Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 7c0eeaa and 8aa9f4c.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (9)

• .github/workflows/integration-tests.yml (1 hunks)
• integrations/upgrade/index.test.ts (1 hunks)
• integrations/utils.ts (2 hunks)
• package.json (1 hunks)
• packages/@tailwindcss-upgrade/src/codemods/css/migrate-at-apply.test.ts (2 hunks)
• packages/@tailwindcss-upgrade/src/codemods/template/is-safe-migration.test.ts (1 hunks)
• packages/tailwindcss/src/canonicalize-candidates.test.ts (26 hunks)
• vitest.config.ts (1 hunks)
• vitest.workspace.ts (0 hunks)

💤 Files with no reviewable changes (1)

• vitest.workspace.ts

🧰 Additional context used

🧬 Code graph analysis (3)

packages/@tailwindcss-upgrade/src/codemods/css/migrate-at-apply.test.ts (1)

packages/@tailwindcss-upgrade/src/codemods/css/migrate-at-apply.ts (1)

• migrateAtApply (7-61)

packages/tailwindcss/src/canonicalize-candidates.test.ts (1)

integrations/utils.ts (1)

• candidate (534-544)

packages/@tailwindcss-upgrade/src/codemods/template/is-safe-migration.test.ts (1)

packages/@tailwindcss-upgrade/src/stylesheet.ts (1)

• designSystem (278-285)

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• GitHub Check: macOS
• GitHub Check: Windows
• GitHub Check: macOS / cli
• GitHub Check: macOS / oxide
• GitHub Check: macOS / vite
• GitHub Check: macOS / upgrade
• GitHub Check: Windows / cli
• GitHub Check: Windows / postcss
• GitHub Check: Windows / upgrade
• GitHub Check: Windows / vite

🔇 Additional comments (8)

packages/@tailwindcss-upgrade/src/codemods/css/migrate-at-apply.test.ts (2)

16-20: Approve perf workaround, but verify it doesn't affect test accuracy.

The @theme { --*: initial; } block is a reasonable short-term fix for the timeout issues mentioned in the PR objectives. However, ensure that resetting all theme tokens doesn't inadvertently mask bugs in theme-dependent migration logic.

The TODO comment suggests this is temporary—consider opening an issue to track investigation of the root cause (canonicalization cache performance) so this workaround can eventually be removed.

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93-133: LGTM—timeout and inline helper address known performance issues.

The explicit 10-second timeout and inlined migrateWithPrefix helper are appropriate given the PR's timeout context. The perf theme block duplication (lines 105-108) is necessary because this test loads a different design system configuration (with prefix(tw)).

Monitor that tests consistently complete well within the 10-second timeout. If tests still approach or exceed this limit, it may indicate that the perf workaround isn't sufficient or that deeper performance issues need investigation.

integrations/utils.ts (1)

40-40: LGTM! Clean implementation of per-test timeout support.

The optional timeout field and fallback pattern (config.timeout ?? TEST_TIMEOUT) allows individual tests to override the default timeout while maintaining backward compatibility. This is particularly useful for tests that inherently take longer to execute.

Also applies to: 90-90

vitest.config.ts (1)

1-8: LGTM! Clear test discovery configuration.

The configuration appropriately:

• Includes all package tests via glob pattern
• Excludes integration tests (run separately via test:integrations script in the workflow)
• Filters out tsconfig.base.json to avoid treating it as a test project

The separation of integration tests aligns with the updated CI workflow structure.

.github/workflows/integration-tests.yml (1)

106-107: Verify CI execution time impact of removing test sharding.

The workflow simplifies from three sharded steps to one combined test per integration. While this improves clarity, it may increase total CI execution time if the previous sharding provided parallelization benefits within each integration.

Monitor the CI execution time for a few runs to ensure this change doesn't significantly increase build times. The matrix already provides parallelization across different integrations, so the impact may be minimal, but it's worth confirming.

package.json (1)

61-61: Vitest 4.0.3 is available and secure.

Verification confirms that version 4.0.3 exists on npm registry. The CRITICAL RCE vulnerability published February 4, 2025, does not affect v4.x—it impacts only v1.x (< 1.6.1), v2.x (< 2.1.9), and v3.x (< 3.0.5). The major version upgrade is secure.

packages/@tailwindcss-upgrade/src/codemods/template/is-safe-migration.test.ts (2)

7-8: LGTM: Clean template literal helper.

The String.raw tag function is a standard pattern for avoiding escape sequences in template literals, which is appropriate for CSS strings.

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10-22: ****

The --*: initial; pattern on line 16 is a documented Tailwind CSS v4 feature for completely disabling all default theme-driven utilities—not an undocumented pattern. The identical values for --shadow and --shadow-sm on lines 17–18 do not affect test accuracy since the test cases only verify detection of the shadow token, not shadow-sm. The inline CSS approach is a sound performance optimization that aligns with the PR's goal of addressing test timeouts.

No changes needed; the code is correct.

Likely an incorrect or invalid review comment.