QA Vitest Writer

QA Vitest Writer

Purpose

Write Vitest unit and integration tests from test case specifications. Transform structured test cases (from qa-testcase-from-docs, qa-manual-test-designer, or specs) into executable Vitest code with proper mocking, fixtures, and assertions.

Trigger Phrases

• "Write Vitest tests for [module/feature]"
• "Generate Vitest unit tests from test cases"
• "Create Vitest integration tests"
• "Add Vitest tests for [spec/requirements]"
• "Migrate Jest tests to Vitest"
• "Vitest tests with mocks and fixtures"
• "In-source Vitest tests for [component]"
• "Parameterized Vitest tests (test.each)"

Key Advantages

Workflow

1. Read test cases — From specs, requirements, or manual test designs
2. Analyze code — Inspect module under test: exports, dependencies, types
3. Generate tests — Produce describe/it blocks with assertions
4. Add mocks/fixtures — Use vi.mock, vi.fn, vi.spyOn, fixtures as needed
5. Verify — Ensure tests run and pass; fix any config or import issues

Context7 MCP

Use Context7 MCP for current Vitest documentation when:

• API signatures or options are uncertain
• New Vitest features (e.g., vi.hoisted, workspace config) need verification
• Migration from Jest requires up-to-date compatibility notes

Key Patterns

See references/patterns.md for detailed patterns.

Configuration

• Config file: vitest.config.ts or vite.config.ts with test block
• Workspace: vitest.workspace.ts for monorepos
• Coverage: v8 or istanbul via @vitest/coverage-v8 / @vitest/coverage-istanbul

See references/config.md for configuration patterns.

Migration from Jest

ESM: Use vi.hoisted() when variables must be available in vi.mock factory. See references/best-practices.md.

File Naming

• {module}.test.ts — Preferred for unit tests
• {module}.spec.ts — Alternative; common for integration tests
• __tests__/{module}.test.ts — Co-located in source directory

Scope

Can do (autonomous):

• Generate Vitest unit and integration tests from test cases
• Add mocks (vi.mock, vi.fn, vi.spyOn), fixtures, and setup/teardown
• Use test.each for parameterized tests; it.concurrent for parallel runs
• Configure vitest.config.ts and coverage
• Migrate Jest tests to Vitest (syntax and API mapping)
• Call qa-diagram-generator for test flow diagrams if needed

Cannot do (requires confirmation):

• Change production code to satisfy tests
• Add tests for requirements not in source documents
• Override project-level Vitest/Vite config without approval

Will not do (out of scope):

• Execute tests (user runs vitest or npm test)
• Write Playwright/Cypress E2E tests (use qa-playwright-ts-writer)
• Modify CI/CD pipelines

References

• references/patterns.md — ESM mocking, in-source testing, concurrent tests, workspace
• references/assertions.md — Vitest/Chai assertion reference
• references/config.md — vitest.config.ts, coverage, workspace, plugins
• references/best-practices.md — Best practices, Jest migration patterns

Quality Checklist

• Tests match test case steps and expected results
• Mocks are properly scoped (per test or per describe)
• No hardcoded secrets or sensitive data
• Assertions are specific (avoid only toBeTruthy where value matters)
• beforeEach/afterEach restore state; mocks reset where needed
• File naming follows project convention (*.test.ts or *.spec.ts)
• Imports use ESM (import); no require unless required by dependency
• Coverage targets considered if specified in requirements

Troubleshooting