محلل الاختبارات

describe('calculateDiscount', () => {
  it('applies 10% for orders over $100', () => {
    expect(calculateDiscount(150)).toBe(15)
  })

  it('applies 5% for orders over $50', () => {
    expect(calculateDiscount(75)).toBe(3.75)
  })

  // What about $0? Negative? Exactly $50? $100?
})

اختبارات الحدود مفقودة: $0، $50، $100، سالب

describe('calculateDiscount', () => {
  it('applies 10% for orders over $100', () => {
    expect(calculateDiscount(150)).toBe(15)
  })

  it('applies 5% for orders over $50', () => {
    expect(calculateDiscount(75)).toBe(3.75)
  })

  it('returns 0 for orders at boundary', () => {
    expect(calculateDiscount(50)).toBe(0)
    expect(calculateDiscount(100)).toBe(5) // 5% tier
  })

  it('handles zero and negative gracefully', () => {
    expect(calculateDiscount(0)).toBe(0)
    expect(calculateDiscount(-10)).toBe(0)
  })
})

إضافة حالات حدية للحدود والمدخلات غير الصالحة

it('shows notification after save', async () => {
  await user.click(saveButton)

  // Flaky! Depends on timing
  await waitFor(() => {
    expect(screen.getByText('Saved!')).toBeVisible()
  })

  // Even worse: arbitrary timeout
  await new Promise(r => setTimeout(r, 100))
  expect(notificationCount).toBe(1)
})

مهلات عشوائية وافتراضات توقيت

it('shows notification after save', async () => {
  await user.click(saveButton)

  // Wait for specific state change
  await waitFor(() => {
    expect(screen.getByRole('alert')).toHaveTextContent('Saved!')
  })

  // Assert on observable behavior, not timing
  expect(
    await screen.findByRole('alert', { name: /saved/i })
  ).toBeVisible()
})

انتظر تغييرات الحالة الملاحظة، وليس الوقت

let testUser: User

beforeAll(async () => {
  // Shared across ALL tests — mutations leak!
  testUser = await createUser({ name: 'Test' })
})

it('updates user name', async () => {
  await updateUser(testUser.id, { name: 'Updated' })
  // Now testUser.name is 'Updated' for all following tests
})

it('checks original name', () => {
  // FAILS! Previous test mutated shared state
  expect(testUser.name).toBe('Test')
})

الحالة المشتركة في beforeAll تتسرب بين الاختبارات

describe('user updates', () => {
  let testUser: User

  beforeEach(async () => {
    // Fresh user for EACH test
    testUser = await createUser({ name: 'Test' })
  })

  afterEach(async () => {
    await deleteUser(testUser.id)
  })

  it('updates user name', async () => {
    await updateUser(testUser.id, { name: 'Updated' })
    expect(testUser.name).toBe('Updated')
  })

  it('checks original name', () => {
    // Works! Fresh testUser with original name
    expect(testUser.name).toBe('Test')
  })
})

استخدم beforeEach لعزل الاختبارات