Test Coverage Analysis

Source: affaan-m/everything-claude-code Original files: commands/test-coverage.md, rules/common/testing.md Curated: 2026-02-21

Minimum Coverage: 80%

All three test types are required:

1. Unit Tests -- Individual functions, utilities, components
2. Integration Tests -- API endpoints, database operations
3. E2E Tests -- Critical user flows

Framework Detection

Workflow

Step 1: Analyze Coverage

1. Run the coverage command
2. Parse output (JSON summary or terminal)
3. List files below 80%, sorted worst-first
4. For each under-covered file, identify untested functions, missing branches, and dead code

Step 2: Generate Tests

Priority order:

1. Happy path -- Core functionality with valid inputs
2. Error handling -- Invalid inputs, missing data, failures
3. Edge cases -- Empty arrays, null/undefined, boundary values
4. Branch coverage -- Each if/else, switch, ternary

Rules:

• Place tests adjacent to source (foo.ts -> foo.test.ts)
• Match existing project patterns
• Mock external dependencies
• Each test must be independent
• Use descriptive names: test_create_user_with_duplicate_email_returns_409

Step 3: Verify

1. Run full test suite -- all must pass
2. Re-run coverage -- verify improvement
3. Repeat if still below 80%

Step 4: Report

Coverage Report
------------------------------
File                   Before  After
src/services/auth.ts   45%     88%
src/utils/validation.ts 32%    82%
------------------------------
Overall:               67%     84%

TDD Workflow (Mandatory)

1. Write test first (RED)
2. Run test -- should FAIL
3. Write minimal implementation (GREEN)
4. Run test -- should PASS
5. Refactor (IMPROVE)
6. Verify coverage (80%+)

Focus Areas

• High cyclomatic complexity functions
• Error handlers and catch blocks
• Utility functions used across the codebase
• API endpoint handlers
• Edge cases: null, undefined, empty string, empty array, zero, negative numbers

Troubleshooting

1. Use the tdd-guide agent
2. Check test isolation
3. Verify mocks are correct
4. Fix implementation, not tests (unless tests are wrong)