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✅ Master Level
Unit Testing
Complete Beginner → Advanced Syllabus (Pin-to-Pin)
🟢 LEVEL 1 — Foundations
1. Introduction to Unit Testing
- What is a unit test
- Purpose: verify individual components
- Unit test granularity
- Test-driven development (TDD)
- Benefits: confidence & regression prevention
2. Testing Frameworks
- Jest for JavaScript
- Mocha for Node.js
- pytest for Python
- JUnit for Java
🟢 LEVEL 2 — Test Anatomy
3. Arrange-Act-Assert Pattern
- Arrange: setup test data
- Act: execute function
- Assert: verify results
- Clear test structure
4. Assertions & Matchers
- Equality assertions
- Boolean assertions
- Thrown errors
- Custom matchers
🟡 LEVEL 3 — Mocking & Stubbing
5. Mock Objects
- Creating mocks
- Mock expectations
- Verifying calls
- Argument matchers
6. Stubs & Spies
- Stub implementation
- Spy on function calls
- Call verification
- Return value stubbing
🟡 LEVEL 4 — Fixtures & Setup
7. Test Fixtures
- Setup & teardown
- BeforeEach & afterEach
- BeforeAll & afterAll
- Fixture inheritance
8. Test Data
- Minimal test data
- Factory functions
- Fixture builders
- Parameterized tests
🟠 LEVEL 5 — Coverage & Completeness
9. Code Coverage
- Line coverage
- Branch coverage
- Function coverage
- Statement coverage
10. Coverage Analysis
- Istanbul for JavaScript
- Coverage reports
- Coverage gaps
- Coverage targets
🟠 LEVEL 6 — Edge Cases & Error Testing
11. Boundary Testing
- Edge case identification
- Boundary value analysis
- Off-by-one errors
- Null & undefined handling
12. Error Testing
- Exception testing
- Error handling paths
- Invalid input testing
- Recovery testing
🔵 LEVEL 7 — Async & Performance
13. Async Testing
- Promises testing
- Async/await testing
- Callback testing
- Timeout handling
14. Performance Testing
- Execution time limits
- Memory leak detection
- Performance regression
- Benchmarking
🔴 LEVEL 8 — Dependency Management
15. External Dependencies
- Mocking external APIs
- Database mocking
- HTTP mocking
- File system mocking
16. Isolation Strategies
- Dependency injection
- Service locator pattern
- Constructor injection
- Factory injection
🔴 LEVEL 9 — Best Practices & Maintenance
17. Test Quality
- DRY principle in tests
- Readability & clarity
- Single responsibility
- Test naming conventions
18. Test Maintenance
- Keeping tests updated
- Flaky test elimination
- Test refactoring
- Deprecation handling
⭐ Senior Frontend Focus (Must Master)
- React component unit testing (React Testing Library)
- Hook testing strategies
- Redux reducer testing
- Utility function testing
- DOM event simulation
- Snapshot testing limitations & best practices
- Coverage targets for UI code