Test File Conventions

When to Apply This Skill

Use this pattern when you need to:

• Write or refactor *.test.ts files in this codebase.
• Structure tests with setup() functions instead of mutable beforeEach setup.
• Split large test files into focused behavior/type/scenario files.
• Enforce behavior-based test naming and clear failure intent.
• Add or review negative type tests using @ts-expect-error.
• Audit a test file for assertions that cannot fail or fakes that don't earn their lines.
• Prune tests that cannot name a real regression they would catch.

References

Load these on demand based on what you're working on: