Phase 1: Coverage Analysis
    ↓
Phase 2: Critical Path Identification
    ↓
Phase 3: Test Pyramid Planning
    ↓
Phase 4: Test Prioritization
    ↓
Phase 5: Edge Case Planning
    ↓
Phase 6: Flaky Test Remediation
    ↓
Phase 7: Implementation Roadmap

npm test -- --coverage
# or
npx vitest run --coverage

pytest --cov=src --cov-report=html

go test -cover ./...
go test -coverprofile=coverage.out ./...
go tool cover -html=coverage.out

cargo tarpaulin --out Html

Lowest Coverage Files:
1. src/auth/oauth.ts - 12% (critical!)
2. src/api/payments.ts - 28% (critical!)
3. src/services/email.ts - 35%
4. src/utils/validation.ts - 42%
5. src/api/users.ts - 48%

src/auth/login.ts        - 45% coverage
src/auth/session.ts      - 52% coverage
src/auth/middleware.ts   - 88% coverage
src/models/user.ts       - 72% coverage

Authentication Path:
- Total lines: 450
- Covered lines: 267
- Coverage: 59% (target: 90%)
- Gap: 183 lines to cover

         /\
        /  \
       / E2E \         10% - Slow, expensive, covers user flows
      /______\
     /        \
    /Integration\      20% - Medium speed, covers integrations
   /______________\
  /                \
 /    Unit Tests    \  70% - Fast, cheap, covers logic
/____________________\

Current State:
- Unit tests: 45 (60%)
- Integration: 25 (33%)
- E2E: 5 (7%)

Ideal State:
- Unit tests: 70 (70%)
- Integration: 20 (20%)
- E2E: 10 (10%)

Gap:
- Need +25 unit tests
- Need -5 integration tests (or OK)
- Need +5 E2E tests

## Test Backlog

### P0 - Immediate (This Sprint)
- [ ] Unit: payment.processPayment()
- [ ] Unit: auth.validateToken()
- [ ] Integration: POST /api/payments
- [ ] E2E: Complete checkout flow

### P1 - High (Next Sprint)
- [ ] Unit: auth.refreshToken()
- [ ] Unit: user.validateEmail()
- [ ] Integration: GET /api/users/:id
- [ ] E2E: Registration flow

### P2 - Medium (Backlog)
- [ ] Unit: validation helpers
- [ ] Unit: formatting utilities
- [ ] Integration: Search API

### P3 - Low (Nice to Have)
- [ ] Unit: logging utilities
- [ ] Unit: config loaders

## Sprint 1: Critical Path (2 weeks)

### Goals
- Achieve 90% coverage on authentication
- Achieve 90% coverage on payments
- Add 5 E2E tests for critical paths

### Tasks
1. Unit tests for auth module (20 tests)
2. Unit tests for payment module (15 tests)
3. Integration tests for auth API (5 tests)
4. E2E test: Complete checkout (1 test)
5. E2E test: Login flow (1 test)

### Expected Outcome
- Overall coverage: 55% → 65%
- Critical path coverage: 59% → 90%

describe('Module or Function', () => {
  // Setup
  beforeEach(() => {
    // Reset state
  });

  describe('method or scenario', () => {
    it('should [expected behavior] when [condition]', () => {
      // Arrange
      const input = createTestInput();

      // Act
      const result = functionUnderTest(input);

      // Assert
      expect(result).toEqual(expectedOutput);
    });
  });
});

should [expected behavior] when [condition]

Examples:
- should return user when valid ID provided
- should throw error when user not found
- should update timestamp when saving

# Node.js
npm test -- --coverage --coverageReporters=text-summary

# Python
pytest --cov=src --cov-report=term-missing

# Go
go test -cover ./... | grep -E "coverage:"

# Rust
cargo tarpaulin --out Stdout

describe('functionName', () => {
  it('should [behavior] when [condition]', () => {
    const result = functionName(input);
    expect(result).toEqual(expected);
  });
});

describe('POST /api/resource', () => {
  it('should create resource when valid data', async () => {
    const response = await request(app)
      .post('/api/resource')
      .send(validData);
    expect(response.status).toBe(201);
  });
});