Unit Testing Skill

When to use

• •When the user asks to "write tests", "add unit tests", "test this function".
• •When creating new modules that require verification.

Instructions

1. Test Runner

• •Use Bun's built-in test runner (bun test).
• •Do NOT install Jest or Mocha unless explicitly requested.

2. File Conventions

• •Place tests in the test/ directory or alongside source files (e.g., src/foo.test.ts) depending on project structure.
• •Naming convention: *.test.ts or *.spec.ts.

3. Syntax & Imports

• •Import test utilities from bun:test:
  typescript

  import { describe, it, expect, beforeEach, afterEach } from 'bun:test';
  

• •Use describe blocks to group tests by function or module.
• •Use it or test for individual test cases.

4. Mocking

• •Use mock from bun:test for function mocking.
  typescript

  import { mock } from 'bun:test';
  const myMock = mock(() => 'value');
  

• •Reset mocks in afterEach if necessary.

5. Execution

• •Run all tests: bun test
• •Run specific file: bun test path/to/file.test.ts
• •Run/Watch mode: bun test --watch

6. Best Practices

• •Isolation: Tests should not depend on each other.
• •Clarity: Test names should describe the expected behavior (e.g., it('should return 404 when user not found')).
• •Coverage: Aim to test both success and failure paths.