test-writer

SKILL.md

---
name: test-writer
description: Use when writing or updating tests. Picks the right matcher style for the project and avoids brittle assertions.
---

# Test writer

Detect the test framework in use (vitest, jest, playwright, ...). Match its idioms — don't introduce a new framework on a whim.

For unit tests:
1. One `describe` per public function, one `it` per scenario.
2. Avoid testing implementation details — assert on observable behaviour.
3. Use object-contains matchers instead of deep-equal when the object has fields you don't care about.
4. Mock at the boundary (HTTP, DB), not internal modules.

For integration tests, isolate the feature: don't share fixtures unless the test suite already does.

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