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Kodelyth ECC
Command

/test-coverage

Analyze test coverage and identify the highest-value gaps to fill

Run:/test-coverage

Test Coverage

Analyze test coverage, identify gaps, and generate missing tests to reach 80%+ coverage.

Step 1: Detect Test Framework

| Indicator | Coverage Command | |-----------|-----------------| | jest.config.* or package.json jest | npx jest --coverage --coverageReporters=json-summary | | vitest.config.* | npx vitest run --coverage | | pytest.ini / pyproject.toml pytest | pytest --cov=src --cov-report=json | | Cargo.toml | cargo llvm-cov --json | | pom.xml with JaCoCo | mvn test jacoco:report | | go.mod | go test -coverprofile=coverage.out ./... |

Step 2: Analyze Coverage Report

  • Run the coverage command
  • Parse the output (JSON summary or terminal output)
  • List files below 80% coverage, sorted worst-first
  • For each under-covered file, identify:
- Untested functions or methods - Missing branch coverage (if/else, switch, error paths) - Dead code that inflates the denominator

Step 3: Generate Missing Tests

For each under-covered file, generate tests following this priority:

  • Happy path — Core functionality with valid inputs
  • Error handling — Invalid inputs, missing data, network failures
  • Edge cases — Empty arrays, null/undefined, boundary values (0, -1, MAX_INT)
  • Branch coverage — Each if/else, switch case, ternary

Test Generation Rules

  • Place tests adjacent to source: foo.ts → foo.test.ts (or project convention)
  • Use existing test patterns from the project (import style, assertion library, mocking approach)
  • Mock external dependencies (database, APIs, file system)
  • Each test should be independent — no shared mutable state between tests
  • Name tests descriptively: test_create_user_with_duplicate_email_returns_409

Step 4: Verify

  • Run the full test suite — all tests must pass
  • Re-run coverage — verify improvement
  • If still below 80%, repeat Step 3 for remaining gaps

Step 5: Report

Show before/after comparison:

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

Focus Areas

  • Functions with complex branching (high cyclomatic complexity)
  • Error handlers and catch blocks
  • Utility functions used across the codebase
  • API endpoint handlers (request → response flow)
  • Edge cases: null, undefined, empty string, empty array, zero, negative numbers

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