End-to-End Testing Best Practices

What is E2E Testing?

End-to-End (E2E) testing simulates real user journeys through your entire app — from clicking buttons to checking results — ensuring everything works together.

Popular E2E Tools

Tool	Note
Playwright	Modern, fast, by Microsoft
Cypress	Great DX, popular
Selenium	Mature, multi-language

A Playwright Test

test("user can log in", async ({ page }) => {
  await page.goto("/login");
  await page.fill("#email", "user@test.com");
  await page.fill("#password", "secret");
  await page.click("button[type=submit]");
  await expect(page).toHaveURL("/dashboard");
});

Best Practices

• Test critical user flows (login, checkout).
• Use stable selectors (data-testid, not CSS classes).
• Keep tests independent.
• Run in CI before deployment.

Avoid Flaky Tests

• Wait for elements properly (no fixed sleeps).
• Reset state between tests.

FAQs

How many E2E tests?

Few — just critical paths. They're slow, so rely on unit tests for the rest. More in our Testing guides.

Cypress or Playwright?

Both excellent; Playwright supports more browsers and is faster.