Improving tests

Test Improvement

Follow the base skill. This Claude overlay only defines tool use and execution details.

Improve tests through public behavior seams. Treat suite latency as a quality attribute. Do not inflate coverage with low-value assertions. Do not change production behavior unless the selected TDD slice requires it.

Arguments

• review: find weak, duplicate, brittle, missing, slow, or flaky tests.
• refactor: simplify tests without changing covered behavior.
• coverage: add useful tests for uncovered business behavior or error paths.
• tdd: one red-green-refactor slice at a time.
• performance: measure slow tests and remove speed waste without weakening behavior.
• full: review, refactor, performance, and add coverage.

If mode is missing, use AskUserQuestion with those options. Ask before adding a new test framework.

Use TaskCreate and TaskUpdate when the session has more than two steps:

1. Choose mode and scope.
2. Inspect test structure and project conventions.
3. Select behavior seam.
4. Apply one cluster or one TDD slice.
5. Verify and report.

Tool order

1. Use Read, Grep, Glob, and LS to find tests, fixtures, helpers, and nearby patterns.
2. Load only matching language references. For performance mode or slow-suite work, also load the matching references/<language>-performance.md when present.
3. Run the narrow test or coverage command only when it helps the selected mode.
4. Use Edit for existing tests and Write only for new files.
5. Run the relevant verification before final output.

Use direct reads/search for small scopes. Spawn read-only agents only for broad or mixed-language audits.

Command discipline

Use only commands supported by the repo and available tools. Examples:

go test ./pkg -run TestName
go test ./...
go tool cover -func=/tmp/coverage.out
golangci-lint run ./...
vitest run path/to/file.test.ts
jest path/to/file.test.ts --runInBand
pytest -q --maxfail=1 --tb=short
pytest -q --durations=10 --durations-min=0.5
uv run pytest -q --maxfail=1 --tb=short
bun test
bun run tsc --noEmit
npm test
npx playwright test --list
bunx playwright test --list

If a referenced command is unavailable, report it as skipped with the exact reason. Do not install a test framework or tool without user approval.

TDD mode

For tdd, write one failing test for one behavior, confirm it fails for the expected reason, implement the smallest passing code, then refactor only while green. Do not write a bulk suite for imagined future behavior.

Scope control

• Test through public module, package, API, CLI, component, or service boundaries.
• Mock only system boundaries.
• Remove real sleeps, external I/O, broad discovery, repeated setup, and coverage-on-default before reducing checks.
• Delete shallow duplicates only after stronger public-boundary tests cover them.
• Do not force table-driven, parametrized, or it.each consolidation when separate tests make distinct behavior clearer.
• If no safe behavior seam exists, use BLOCKED or Proposed Changes.