write-tests

name	write-tests
description	Write colocated tests for React + Express + TypeScript code using the project's runner, conventions, mocked repository interfaces, React Testing Library, and TanStack Query patterns.
when_to_use	Use WHEN adding tests, improving coverage, or testing a module, service, hook, component, route, or feature — whether the user asks directly or an implementation agent is realizing a Testing To-Do item from a `tasks/task-N.md` plan. Do NOT use to run an existing suite (use /run-checks), and do NOT use for browser end-to-end flows (those are Playwright specs in `e2e/` — use /e2e).
argument-hint	[path-to-test]
arguments	["target"]
model	sonnet

Write tests to convention

Test $target. Colocate tests.

Step 1 — Detect runner and style

bash "${CLAUDE_PROJECT_DIR}/.claude/lib/detect-toolchain.sh"

Open nearby tests first. Match imports, setup, mocks, naming, and references/test-patterns.md.

Step 2 — Pick the test type

• Service tests use a mocked repository interface and no DB or HTTP.
• Repository tests are integration tests only when the project already has a test DB harness.
• Query-backed hooks and components use React Testing Library with a fresh QueryClient and retry: false.
• Presentational components render with props and assert by role, label, or text.
• Route tests use the project's existing supertest-style pattern when one exists.

Step 3 — Write behavior tests

Use Arrange-Act-Assert. Test observable outcomes, including meaningful error or edge cases, not private internals.

Step 4 — Run new tests

source "${CLAUDE_PROJECT_DIR}/.claude/lib/detect-toolchain.sh"
run_tests <new-test-path>

Iterate until tests pass. Report covered behaviors, not a coverage percentage.

Checklist

• Runner and local test style were detected.
• Test file is colocated with the code under test.
• Services use a mocked repository interface.
• Query-backed UI uses a fresh QueryClient with retry: false.
• Assertions target user-visible behavior or boundary calls.
• New tests pass through the detected runner.