a11y-playwright-testing（a11y Playwright 测试）

Playwright Accessibility Testing (TypeScript)

Comprehensive toolkit for automated accessibility testing using Playwright with TypeScript and axe-core. Enables WCAG 2.1 Level AA compliance verification, keyboard operability testing, semantic validation, and accessibility regression prevention.

Activation: This skill is triggered when working with accessibility testing, WCAG compliance, axe-core scans, keyboard navigation tests, focus management, ARIA validation, or screen reader compatibility.

When to Use This Skill

• Automated a11y scans with axe-core for WCAG 2.1 AA compliance
• Keyboard navigation tests for Tab/Enter/Space/Escape/Arrow key operability
• Focus management validation for dialogs, menus, and dynamic content
• Semantic structure assertions for landmarks, headings, and ARIA
• Form accessibility testing for labels, errors, and instructions
• Color contrast and visual accessibility verification
• Screen reader compatibility testing patterns

Prerequisites

Quick Setup

# Add axe-core to existing Playwright project
npm install -D @axe-core/playwright axe-core

First Questions to Ask

Before writing accessibility tests, clarify:

1. Scope: Which pages/flows are in scope? What's explicitly excluded?
2. Standard: WCAG 2.1 AA (default) or specific organizational policy?
3. Priority: Which components are highest risk (forms, modals, navigation, checkout)?
4. Exceptions: Known constraints (legacy markup, third-party widgets)?
5. Assistive Tech: Which screen readers/browsers need manual testing?

Core Principles

1. Automation Limitations

⚠️ Critical: Automated tooling can detect ~30-40% of accessibility issues. Use automation to prevent regressions and catch common failures; manual audits are required for full WCAG conformance.

2. Semantic HTML First

Prefer native HTML semantics over ARIA. Use ARIA only when native elements cannot achieve the required semantics.

// ✅ Semantic HTML - inherently accessible
await page.getByRole("button", { name: "Submit" }).click();

// ❌ ARIA override - requires manual keyboard/focus handling
await page.locator('[role="button"]').click(); // Often a <div>

3. Locator Strategy as A11y Signal

If you cannot locate an element by role or label, it's often an accessibility defect.

Key Workflows

Automated Axe Scan (WCAG 2.1 AA)

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

test("page has no WCAG 2.1 AA violations", async ({ page }) => {
  await page.goto("/");

  const results = await new AxeBuilder({ page })
    .withTags(["wcag2a", "wcag2aa", "wcag21a", "wcag21aa"])
    .analyze();

  expect(results.violations).toEqual([]);
});

Scoped Axe Scan (Component-Level)

test("form component is accessible", async ({ page }) => {
  await page.goto("/contact");

  const results = await new AxeBuilder({ page })
    .include("#contact-form") // Scope to specific component
    .withTags(["wcag2a", "wcag2aa", "wcag21a", "wcag21aa"])
    .analyze();

  expect(results.violations).toEqual([]);
});

Keyboard Navigation Test

test("form is keyboard navigable", async ({ page }) => {
  await page.goto("/login");

  // Tab to first field
  await page.keyboard.press("Tab");
  await expect(page.getByLabel("Email")).toBeFocused();

  // Tab to password
  await page.keyboard.press("Tab");
  await expect(page.getByLabel("Password")).toBeFocused();

  // Tab to submit button
  await page.keyboard.press("Tab");
  await expect(page.getByRole("button", { name: "Sign in" })).toBeFocused();

  // Submit with Enter
  await page.keyboard.press("Enter");
  await expect(page).toHaveURL(/dashboard/);
});

Dialog Focus Management

test("dialog traps and returns focus", async ({ page }) => {
  await page.goto("/settings");
  const trigger = page.getByRole("button", { name: "Delete account" });

  // Open dialog
  await trigger.click();
  const dialog = page.getByRole("dialog");
  await expect(dialog).toBeVisible();

  // Focus should be inside dialog
  await expect(dialog.getByRole("button", { name: "Cancel" })).toBeFocused();

  // Tab should stay trapped in dialog
  await page.keyboard.press("Tab");
  await expect(dialog.getByRole("button", { name: "Confirm" })).toBeFocused();
  await page.keyboard.press("Tab");
  await expect(dialog.getByRole("button", { name: "Cancel" })).toBeFocused();

  // Escape closes and returns focus to trigger
  await page.keyboard.press("Escape");
  await expect(dialog).toBeHidden();
  await expect(trigger).toBeFocused();
});

Skip Link Validation

test("skip link moves focus to main content", async ({ page }) => {
  await page.goto("/");

  // First Tab should focus skip link
  await page.keyboard.press("Tab");
  const skipLink = page.getByRole("link", { name: /skip to (main|content)/i });
  await expect(skipLink).toBeFocused();

  // Activating skip link moves focus to main
  await page.keyboard.press("Enter");
  await expect(page.locator('#main, [role="main"]').first()).toBeFocused();
});

POUR Principles Reference

Axe-Core Tags Reference

Default Tags (WCAG 2.1 AA)

const WCAG21AA_TAGS = ["wcag2a", "wcag2aa", "wcag21a", "wcag21aa"];

Exception Handling

When exceptions are unavoidable:

1. Scope narrowly - specific component/route only
2. Document impact - which WCAG criterion, user impact
3. Set expiration - owner + remediation date
4. Track ticket - link to remediation issue

// ❌ Avoid: Global rule disable
new AxeBuilder({ page }).disableRules(["color-contrast"]);

// ✅ Better: Scoped exclusion with documentation
new AxeBuilder({ page })
  .exclude("#third-party-widget") // Known issue: JIRA-1234, fix by Q2
  .withTags(["wcag2a", "wcag2aa", "wcag21a", "wcag21aa"])
  .analyze();

Troubleshooting

CLI Quick Reference

Common Rationalizations

Common shortcuts and "good enough" excuses that erode test quality — and the reality behind each.

References

External Resources

Verification

After completing this skill's workflow, confirm:

• axe-core audit passes — AxeBuilder.analyze() returns zero violations
• Keyboard navigation tested — All interactive elements reachable via Tab; focus order is logical
• ARIA attributes valid — No duplicate IDs, no missing labels, roles match element types
• Color contrast sufficient — WCAG 2.1 AA minimum contrast ratios met (4.5:1 normal text, 3:1 large text)
• Screen reader compatible — All images have alt text; form inputs have labels; landmarks present
• Accessibility scan integrated in CI — Accessibility tests run as part of the standard CI pipeline
• Violation report generated — Axe results saved to file for review and tracking