nikoheikkila/playwright

End-to-End Testing with Playwright

• Location: Playwright tests are located under src/__tests__/feature/
• Strategy: Tests primary user flows and critical functionality
• Configuration: playwright.config.ts with local/CI environments

Test Design Guidelines

Locator Strategy (Priority Order)

1. Prefer Role-based locators: Use page.getByRole("button", { name: "Submit" }) to select buttons by their accessible name
2. Test IDs: Use page.getByTestId("submit-button") to select dynamic elements with data-testid attributes
3. Text content: Use page.getByText("Click me") to select elements based on visible text
4. Label association: Use page.getByLabel("Email address") to select form fields based on their associated labels
5. CSS selectors: Use only as last resort and with specific justification

Structural Requirements

// Required imports and fixture structure
import { test, expect, type Page } from "@playwright/test";

test.describe.parallel("Given I want to test feature X", () => {
  test.beforeEach(async ({ page }) => {
    await page.goto("/target-page");
  });

  test("when I perform action Y, then outcome Z should occur", async ({ page }) => {
    await test.step("Descriptive step name", async () => {
      // Test implementation
    });
  });
});

// For mobile test suites, configure viewport at the describe level
test.describe.parallel("Given I visit the page using a mobile browser", () => {
  test.use({
    hasTouch: true,
    viewport: { width: 375, height: 667 },
  });

  // Tests here run with mobile viewport
});

Required Practices

Critical: These are mandatory practices to follow.

• ✅ Use test.step() to organize test actions and improve reporting
• ✅ Create fixtures objects for test-specific configuration values
• ✅ Use await expect(locator).toBeVisible() for auto-retrying assertions
• ✅ Group related tests with test.describe.parallel()
• ✅ Test mobile viewports with test.use({ viewport: { width: 375, height: 667 }, hasTouch: true })
• ✅ Wait for elements to become visible rather than using timeouts
• ✅ Test keyboard navigation for accessibility compliance

Anti-Patterns

Critical: Avoid these at all costs.

• ❌ page.waitForTimeout() - Never use hard-coded timeouts
• ❌ page.locator(".css-class") - Avoid CSS selectors when possible
• ❌ data-testid / data-test-id - Never use test-id attributes; this project requires web-first locators only
• ❌ Inline comments explaining assertions - Use descriptive test steps instead
• ❌ any types - Import proper types like Page from Playwright

Mobile Viewport Testing

• Minimum touch target size: 44px (iOS recommendation)
• Test viewport: 375x667 (iPhone SE) for mobile scenarios
• Verify touch interactions work correctly
• Validate responsive design at multiple breakpoints

Accessibility Testing

• Keyboard navigation must work for all interactive elements
• Use toMatchAriaSnapshot for component structure validation
• Test screen reader compatibility with semantic HTML
• Verify focus management and skip links functionality

Axe-Core Integration

Use @axe-core/playwright to run WCAG 2.2 AA scans in E2E tests. Existing page-archetype scans live in src/__tests__/feature/a11y.test.ts.

import { expect, test, type Page } from "@playwright/test";
import { AxeBuilder } from "@axe-core/playwright";

const WCAG_TAGS = ["wcag2a", "wcag2aa", "wcag21a", "wcag21aa", "wcag22aa"];

test("page passes WCAG 2.2 AA", async ({ page }) => {
  await page.goto("/", { waitUntil: "networkidle" });
  const results = await new AxeBuilder({ page }).withTags(WCAG_TAGS).analyze();
  expect(results.violations).toEqual([]);
});

Notes:

• Always use waitUntil: "networkidle" so React has hydrated and all styles are applied before the scan.
• The region rule is tagged best-practice, not WCAG — it does not run with the WCAG tag filter above.
• Disable a specific rule only when it produces a documented false positive: .disableRules(["rule-id"]).
• E2E scans test the full page with production CSS; they catch color-contrast issues that component tests cannot (component tests lack main.scss).

Blog-Specific Test Patterns

Pagination

// Test pagination with proper edge case handling
const fixtures = {
  postsPerPage: 30,
  pagination: { minimumPostsOnPage: 1 }
};

// Check for dynamic pagination states
const nextPageExists = (await nextPageLink.count()) > 0;
if (nextPageExists) {
  await expect(nextPageLink).toBeVisible();
}

Navigation

// Test burger menu with proper element waiting
const burgerMenuButton = page.locator(".bm-burger-button");
await burgerMenuButton.click();

// Wait for menu to become visible (not timeout)
const menuContainer = page.locator(".bm-menu");
await expect(menuContainer).toBeVisible();

Navigation Helpers

Shared navigation helpers are in src/__tests__/feature/navigate.ts:

import type { Page, Locator } from "@playwright/test";

// Handle popup windows for external links
export const toExternalSiteByClicking = async (page: Page, locator: Locator): Promise<Page> => {
  const popupPromise = page.waitForEvent("popup");
  await locator.click();
  const popup = await popupPromise;
  await popup.waitForLoadState("load");
  return popup;
};

// Navigate to an internal page by clicking a link
export const toInternalPageByClicking = async (page: Page, locator: Locator): Promise<void> => {
  await Promise.all([page.waitForURL(/\//), locator.click()]);
};

Content Validation

// Verify dynamic content differences between pages
const firstPostPage2 = await posts.first().textContent();
await page.goto("/");
const firstPostPage1 = await posts.first().textContent();

expect(firstPostPage1).not.toBe(firstPostPage2);

Troubleshooting

• E2E test failures: Ensure production build exists and content is served from http://localhost:8000 before running E2E tests
• Test timeouts: Playwright configured with 60s timeout in CI, unlimited locally
• Component changes: Always run task build after modifying React components before running E2E tests
• Locator failures: Use accessibility-first locators (getByRole, getByTestId) over CSS selectors
• Element not found: Wait for element visibility with await expect(element).toBeVisible() instead of timeouts
• Mobile test failures: Ensure touch targets meet minimum 44px size for iOS compatibility
• Navigation menu issues: Wait for .bm-menu container visibility, not just overlay
• Pagination edge cases: Handle dynamic pagination states where next/previous links may not exist
• API tests (robots.txt, sitemap): These files are only generated in production builds