e2e

name	e2e
description	Testing E2E strategies based on Clean Architecture layers with cypress. Trigger: Invoke when writing tests E2E or testing user flows, verifying full integration in realistic scenarios.
license	Apache-2.0
metadata	{"author":"jmgomezdev","version":"1.0"}

E2E Testing Fundamentals

What to Test with E2E:

• Critical user journeys (login, checkout, signup)
• Complex interactions (drag-and-drop, multi-step forms)
• Cross-browser compatibility
• Real API integration
• Authentication flows

What NOT to Test with E2E:

• Unit-level logic (use unit tests)
• API contracts (use integration tests)
• Edge cases (too slow)
• Internal implementation details

Best Practices:

Fundamentals:

• Test user behavior, not implementation
• Keep tests independent
• Make tests deterministic
• Optimize for speed
• Use data-testid, not CSS selectors

Test Coverage:

• Critical user paths tested (signup, login, purchase)
• Happy paths covered
• Error scenarios tested
• Edge cases included
• Mobile viewport tested

Test Quality:

• Stable selectors (data-testid, roles)
• No arbitrary timeouts
• No test interdependencies
• Proper waits for async operations
• Clear test descriptions

Use Stable Selectors

// ❌ Brittle - breaks when styling changes
await page.locator('.btn-primary.large').click();
await page.locator('div > div > button:nth-child(2)').click();

// ✅ Semantic - uses accessible roles
await page.getByRole('button', { name: 'Submit' }).click();
await page.getByRole('textbox', { name: 'Email' }).fill('[e-mail]');

// ✅ Test IDs - explicit test hooks
await page.getByTestId('submit-button').click();
await page.getByTestId('email-input').fill('[e-mail]');

// In your component:
<button data-testid="submit-button">Submit</button>
<input data-testid="email-input" type="email" />

Mocking External Services

// ✅ Mock API responses
test('handles API error', async ({ page }) => {
  // Intercept and mock API call
  await page.route('**/api/users', (route) => {
    route.fulfill({
      status: 500,
      body: JSON.stringify({ error: 'Server error' }),
    });
  });

  await page.goto('/users');

  await expect(page.getByText('Failed to load users')).toBeVisible();
});

// ✅ Mock successful response
test('displays user list', async ({ page }) => {
  await page.route('**/api/users', (route) => {
    route.fulfill({
      status: 200,
      body: JSON.stringify({
        users: [
          { id: 1, name: 'Alice' },
          { id: 2, name: 'Bob' },
        ],
      }),
    });
  });

  await page.goto('/users');

  await expect(page.getByText('Alice')).toBeVisible();
  await expect(page.getByText('Bob')).toBeVisible();
});

Resources

• Cypress Documentation

Keywords

e2e, end-to-end, ``.