## Summary
- Updates vitest and @vitest/coverage-v8 from 2.1.8 to 4.0.1
- Fixes test mocks to work with vitest 4.0's constructor support
requirements
## Changes
Vitest 4.0 now supports `vi.fn()` being used as constructors, which
means arrow functions can no longer be used in mock implementations that
will be called as constructors.
### Key refactorings:
- **Class-based mocks in vi.mock()**: Defined mock classes directly in
`vi.mock()` factories instead of using `.mockImplementation()` with
arrow functions
- **Shared mock implementations**: Created shared `vi.fn()` instances
that can be configured per-test, avoiding the need for
`.mockImplementation()`
- **Biome linter compatibility**: The approach avoids
`.mockImplementation()` entirely, preventing biome from converting
`function` keywords back to arrow functions
### Files changed:
- `package.json`, `package-lock.json`: vitest version updates
- `test/app/config-tests.ts`: Refactored CompilerProps mocks with shared
cePropsImpl
- `test/app/main-tests.ts`: Refactored all constructor mocks
(CompilerFinder, FormattingService, CompileHandler, etc.)
## Test plan
- [x] All tests pass with `npm run test-min`
- [x] Linter passes with `npm run lint`
- [x] Type checking passes with `npm run ts-check`
- [x] Pre-commit hooks pass
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Co-authored-by: Claude <noreply@anthropic.com>
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