Test Coverage (command)

Analyze test coverage gaps and generate tests for uncovered code paths. ## Steps ### 1. Run Coverage Analysis - Detect the test framework and run coverage: - **JS/TS**: `npx vitest run --coverage` or `npx jest --coverage` - **Python**: `pytest --cov=src --cov-report=term-missing` - **Go**: `go test -coverprofile=cover.out ./... && go tool cover -func=cover.out` - **Rust**: `cargo tarpaulin --out Stdout` ### 2. Identify Gaps - List files below 80% line coverage. - For each low-coverage file, identify: - Uncovered branches (if/else, switch cases, error paths). - Uncovered functions or methods. - Edge cases not exercised (null inputs, empty collections, boundary values). ### 3. Prioritize - Rank gaps by risk: business logic > data access > utilities > configuration. - Focus on branches where bugs are most likely to hide: error handling, boundary conditions, type coercion. ### 4. Generate Tests - Write tests for the highest-priority uncovered paths. - Each test targets a specific uncovered branch or function. - Use existing test patterns and conventions from the codebase. - Follow the Arrange-Act-Assert structure. ### 5. Verify - Re-run coverage to confirm the gaps are filled. - Ensure no existing tests broke. ## Rules - Do not write tests purely to increase numbers. Every test must assert meaningful behavior. - Exclude generated code, type definitions, and configuration from coverage targets. - Target 80% line coverage and 75% branch coverage as minimums. - If a function is genuinely untestable (e.g., thin wrappers), document why rather than writing a meaningless test.