Testing Standards
[Purpose: guide what to test, where tests live, and how to structure them]
Philosophy
- Test behavior, not implementation
- Prefer fast, reliable tests; minimize brittle mocks
- Cover critical paths deeply; breadth over 100% pursuit
Organization
Options:
- Co-located:
component.tsx + component.test.tsx
- Separate:
/src/... and /tests/...
Pick one as default; allow exceptions with rationale.
Naming:
- Files:
*.test.* or *.spec.*
- Suites: what is under test; Cases: expected behavior
Test Types
- Unit: single unit, mocked dependencies, very fast
- Integration: multiple units together, mock externals only
- E2E: full flows, minimal mocks, only for critical journeys
Structure (AAA)
it('does X when Y', () => {
// Arrange
const input = setup();
// Act
const result = act(input);
// Assert
expect(result).toEqual(expected);
});
Mocking & Data
- Mock externals (API/DB); never mock the system under test
- Use factories/fixtures; reset state between tests
- Keep test data minimal and intention-revealing
Coverage
- Target: [% overall]; higher for critical domains
- Enforce thresholds in CI; exceptions require review rationale
Focus on patterns and decisions. Tool-specific config lives elsewhere.