E2E Testing with Playwright

Execute E2E testing workflows using Playwright MCP.

Use TodoWrite to track these 4 phases:

1. Determine action (parse args or ask)
2. Execute action (run/record/generate/verify)
3. Verify results
4. Present output

Phase 1: Parse Arguments

$ARGUMENTS:

• run → Run existing E2E tests
• record → Record browser session for test generation
• generate → Generate test from URL or page description
• verify <feature> → Verify specific feature works in browser
• (empty) → Ask what to do

If no argument provided, use AskUserQuestion:

Phase 2: Execute Action

Run Tests

npx playwright test

For specific test:

npx playwright test login.spec.ts

For headed mode (visible browser):

npx playwright test --headed

Record Session

Use Playwright MCP tools for browser interaction:

1. browser_navigate - Go to target URL
2. browser_snapshot - Inspect page structure
3. browser_click, browser_type, browser_fill_form - Interact
4. Generate test file with Page Object pattern

Generate Test

Spawn playwright-tester agent:

Task(
  subagent_type="playwright-tester",
  description="Generate E2E test",
  prompt="Generate E2E test for:
  URL: {target URL}
  Flow: {user flow description}

  Requirements:
  - Use Page Object pattern
  - Use semantic locators (getByRole, getByLabel, getByText)
  - Include assertions for expected outcomes
  - No hardcoded waits (use waitFor patterns)
  - Include accessibility checks where appropriate"
)

Verify Feature

Spawn playwright-tester agent for feature verification:

Task(
  subagent_type="playwright-tester",
  description="Verify feature",
  prompt="Verify this feature works correctly in the browser:
  Feature: {feature description}

  Steps:
  1. Navigate to appropriate page
  2. Execute user flow
  3. Assert expected outcomes
  4. Report PASS/FAIL with evidence (screenshots if needed)"
)

Phase 3: Verify Results

npx playwright test --headed

If tests fail, review output and fix issues.

Phase 4: Output

E2E TESTING
===========
Action: {run|record|generate|verify}
Result: {outcome}
Tests: {pass/fail count}

Details:
- [test results or generation summary]

Key Tools

Supported Stacks

• TypeScript: Playwright Test with Page Objects
• Go/HTMX: Test HTMX interactions, form submissions, partial updates

HTMX Testing Tips

• Use browser_snapshot to verify DOM updates after HTMX swaps
• Test hx-trigger, hx-swap, hx-target behaviors
• Verify HX-* response headers in network requests
• Assert partial page updates without full reload

Error Scenarios & Handling

Element Not Found

// BAD: Immediate failure
await page.click("#submit-btn");

// GOOD: Wait with timeout + fallback
const btn = page.locator("#submit-btn");
if ((await btn.count()) === 0) {
  // Try alternative selector
  await page.click('button[type="submit"]');
} else {
  await btn.click();
}

Recovery strategies:

1. Use browser_snapshot to inspect current DOM state
2. Try alternative locators (text, role, data-testid)
3. Check if element is in iframe/shadow DOM
4. Verify page loaded correctly (check URL, title)

Timeout Errors

// Configure timeouts
test.setTimeout(60000); // Test timeout
page.setDefaultTimeout(30000); // Action timeout

// Or per-action
await page.click("#btn", { timeout: 10000 });

Network Issues

// Wait for network idle
await page.waitForLoadState("networkidle");

// Mock failing endpoints
await page.route("**/api/**", (route) => {
  route.fulfill({ status: 500, body: "Server Error" });
});

Flaky Test Patterns

Avoid:

• Fixed page.waitForTimeout(1000) delays
• Brittle selectors like .btn-23
• Tests depending on animation timing

Prefer:

• waitForSelector, waitForLoadState
• Role/text-based selectors: getByRole('button', { name: 'Submit' })
• Retry patterns for known flaky operations

Debugging Failed Tests

1. Get snapshot: browser_snapshot shows accessibility tree
2. Screenshot: Capture current visual state
3. Console logs: Check browser console for JS errors
4. Network tab: Verify API calls succeeded
5. Trace: Enable Playwright trace for post-mortem

# Run with trace
npx playwright test --trace on

# View trace
npx playwright show-trace trace.zip

Execute E2E testing workflow now.