E2E Testing Best Practices (Playwright)

Setup

• Use Playwright helpers from tests/e2e/helpers.ts
• Use data-testid attributes for stable selectors
• Write descriptive test names that explain user behavior
• Ensure tests are isolated and can run independently

Never Use Hard-Coded Timeouts

// Bad
await element.click();
await page.waitForTimeout(200);

// Good
await element.click();
await expect(otherElement).toBeVisible();

Use Playwright's Auto-Waiting

// Bad
if (await element.isVisible()) {
  await element.click();
}

// Good
await expect(element).toBeVisible();
await element.click();

Never Use Non-Null Assertions

// Bad
const box = await element.boundingBox();
const x = box!.x;

// Good
const box = await element.boundingBox();
if (!box) {
  throw new Error("Unable to locate element bounding box");
}
const x = box.x;

Don't Await Locators (They're Lazy)

// Bad
const button = await page.getByTestId("submit");

// Good
const button = page.getByTestId("submit");
await expect(button).toBeVisible();

Use Consistent Assertion Patterns

// Bad
expect(await element).toHaveText("text");
expect(await element.isVisible()).toBe(true);

// Good
await expect(element).toHaveText("text");
await expect(element).toBeVisible();

Prefer Semantic Selectors

Priority order:

1. getByRole() - Best for accessibility
2. getByTestId() - Best for test stability (preferred for this app)
3. getByText() - Good for static content
4. locator() with data attributes - When above don't work
5. CSS selectors - Last resort

Test Isolation

• Each test should set up its own state
• Don't depend on test execution order (unless using serial mode intentionally)
• Clean up after tests in afterEach or afterAll

Helper Functions

• Leverage existing helpers from tests/e2e/helpers.ts
• Create new helpers for repeated workflows
• Keep helpers focused and reusable

Add Meaningful Error Context

// Okay
await expect(element).toBeVisible();

// Better
await expect(element, "Component should appear after loading").toBeVisible();

Test User Behavior, Not Implementation

// Bad - implementation detail
await expect(button).toHaveClass("bg-blue-500");

// Good - user-visible behavior
await expect(button).toBeVisible();
await expect(button).toBeEnabled();
await expect(button).toHaveText("Submit");