Testing Skill

This skill activates when writing tests, debugging test failures, or setting up test infrastructure.

Activation Triggers

Engage this skill when:

•User asks to "test" or "write tests"
•User mentions Vitest
•User has failing tests
•User wants to add test coverage
•User asks about mocking or test setup

Test Framework

This repo uses Vitest for testing:

•Config: vitest.workspace.ts at root
•Per-package configs via vitest.config.ts
•Coverage: @vitest/coverage-v8

Commands

bash

# Run all tests
bun run test

# Watch mode
bun run test:watch

# With coverage
bun run test:coverage

# Specific package
bun run --cwd packages/db test

Test Patterns

Basic Test Structure

typescript

import { describe, it, expect, beforeEach, vi } from 'vitest'

describe('myFunction', () => {
  beforeEach(() => {
    vi.clearAllMocks()
  })

  it('should do something', () => {
    const result = myFunction('input')
    expect(result).toBe('expected')
  })

  it('should handle errors', () => {
    expect(() => myFunction(null)).toThrow('Invalid input')
  })
})

Mocking (Bun-Compatible Pattern)

IMPORTANT: vi.mocked() does NOT work with Bun. Define mock functions OUTSIDE vi.mock():

typescript

// CORRECT: Define mock outside vi.mock()
const mockApiMethod = vi.fn()

vi.mock('@funk-tree/api', () => ({
  createClient: vi.fn().mockReturnValue({
    api: { method: mockApiMethod }
  })
}))

describe('test', () => {
  beforeEach(() => {
    vi.clearAllMocks()
  })

  it('should handle success', async () => {
    mockApiMethod.mockResolvedValue({ data: { id: 1 } })
    // Use mockApiMethod directly
  })

  it('should handle error', async () => {
    mockApiMethod.mockRejectedValue(new Error('API Error'))
    // Test error handling
  })
})

typescript

// WRONG: vi.mocked() doesn't work with Bun
vi.mock('@funk-tree/api', () => ({
  createClient: vi.fn()
}))

it('test', async () => {
  const { createClient } = await import('@funk-tree/api')
  vi.mocked(createClient).mockReturnValue(...)  // FAILS
})

Async Testing

typescript

it('should fetch data', async () => {
  const result = await fetchPerson('Funck-6')
  expect(result).toMatchObject({
    id: expect.any(String),
    name: expect.stringContaining('Funck'),
  })
})

Testing Database Operations

typescript

import { db } from '@funk-tree/db'

describe('person queries', () => {
  it('should find person by WikiTree ID', async () => {
    const person = await db.query.persons.findFirst({
      where: eq(persons.wikiTreeId, 'Funck-6')
    })
    expect(person).toBeDefined()
    expect(person?.name).toBe('Heinrich Funck')
  })
})

Key Testing Patterns

Pattern	Status
Define mock outside `vi.mock()`	Works
Use `vi.mocked()`	Does NOT work with Bun
`vi.clearAllMocks()` in `beforeEach`	Required
Mock nested objects via reference	Works

Test File Conventions

•Test files: *.test.ts or *.spec.ts
•Located alongside source: src/myModule.test.ts
•Or in __tests__ directory

Coverage

Coverage is configured per-package. Reports include:

•text - Terminal output
•json - Machine-readable
•html - Browser viewable (coverage/index.html)

Output Style

When this skill is active, I:

•Write complete, runnable test files
•Use proper Bun-compatible mocking patterns
•Include both success and error test cases
•Explain test structure decisions
•Suggest additional test cases