describe('Reader dependency injection', () => {
  const logs: string[] = []
  const mockLogger: Logger = {
    log: (msg) => logs.push(msg),
  }

  const users = [
    { id: 1, name: 'Alice' },
    { id: 2, name: 'Bob' },
  ]

  const mockUserService: UserService = {
    getUser: (id) => users.find(u => u.id === id),
  }

  const deps: Dependencies = {
    logger: mockLogger,
    userService: mockUserService,
  }

  beforeEach(() => {
    logs.length = 0
  })

  it('finds existing user and logs', () => {
    const result = getUserById(1)(deps)
    expect(result).toBe('Alice')
    expect(logs).toContain('Found user: Alice')
  })

  it('handles missing user and logs', () => {
    const result = getUserById(99)(deps)
    expect(result).toBe('User not found')
    expect(logs).toContain('User 99 not found')
  })

  it('works with different user service', () => {
    const differentService: UserService = {
      getUser: () => ({ id: 999, name: 'Test User' }),
    }
    const testDeps = { ...deps, userService: differentService }
    const result = getUserById(1)(testDeps)
    expect(result).toBe('Test User')
  })
})