Frontend E2e User Journeys

Frontend E2E User Journeys

Skill Usage Announcement

MANDATORY: When using this skill, announce it at the start with:

🔧 Using Skill: frontend-e2e-user-journeys | [brief purpose based on context]

Example:

🔧 Using Skill: frontend-e2e-user-journeys | [Provide context-specific example of what you're doing]

This creates an audit trail showing which skills were applied during the session.

Overview

End-to-end (E2E) tests verify complete user workflows from start to finish, including multiple pages, API requests, and database state.

When to use this skill:

• Implementing critical user workflows (login, checkout, signup)
• Testing cross-page journeys (onboarding wizard)
• Verifying third-party integrations (OAuth, payments)
• Testing business-critical flows (cancel subscription, refund)

When NOT to use:

• Component-level behavior → Use component tests
• Edge cases → Use unit tests
• Variations of same flow → Use parameterized tests
• Rapid iteration → E2E tests too slow

The Iron Law

E2E TESTS ONLY FOR CRITICAL USER JOURNEYS

Rule of thumb: If manual QA would test it end-to-end, automate it at E2E level. Otherwise, test at lower level.

Target: E2E tests should be 10-15% of total test suite (not more).

When to Write E2E Tests

Use E2E Tests For:

Critical user workflows:

• ✓ User signup → Email verification → First login
• ✓ Add to cart → Checkout → Payment → Order confirmation
• ✓ Login → Browse products → Add to wishlist
• ✓ Create account → Set preferences → Verify email → Login

Cross-page workflows:

• ✓ Multi-step wizards (onboarding, configuration)
• ✓ Shopping cart persistence across pages
• ✓ Authentication flow across entire app

Third-party integrations:

• ✓ OAuth login (Google, GitHub, etc.)
• ✓ Payment processing (Stripe, PayPal)
• ✓ Email verification flows

Business-critical flows:

• ✓ Cancel subscription
• ✓ Refund order
• ✓ Delete account

DON'T Use E2E Tests For:

• ✗ Edge cases (test at unit level)
• ✗ Component behavior (test with component tests)
• ✗ Validation logic (test at unit level)
• ✗ Every permutation (test logic separately)
• ✗ Rapid development iteration (too slow)

Decision Tree:

Is this a complete user workflow?
├─ YES → Continue
│   ├─ Is it business-critical?
│   │   ├─ YES → E2E test appropriate
│   │   └─ NO → Could this be component test?
│   └─ NO → Use component or unit test
└─ NO → Use component or unit test

Page Object Model Pattern

Encapsulate page interactions in reusable classes:

Why Page Objects?

Benefits:

• Single source of truth for selectors
• Easy to update when UI changes
• Readable tests (domain language)
• Works with Playwright, Selenium, Puppeteer

Pattern:

// pages/LoginPage.ts
export class LoginPage {
  constructor(private page: Page) {}

  // Locators (encapsulated)
  private get emailInput() {
    return this.page.locator('[name="email"]');
  }

  private get passwordInput() {
    return this.page.locator('[name="password"]');
  }

  private get submitButton() {
    return this.page.locator('button[type="submit"]');
  }

  // High-level actions (domain language)
  async goto() {
    await this.page.goto('/login');
  }

  async login(email: string, password: string) {
    await this.emailInput.fill(email);
    await this.passwordInput.fill(password);
    await this.submitButton.click();
  }

  async getErrorMessage(): Promise<string | null> {
    const alert = this.page.locator('[role="alert"]');
    return await alert.textContent();
  }

  async isLoggedIn(): Promise<boolean> {
    return await this.page.locator('[data-testid="user-menu"]').isVisible();
  }
}

Using Page Objects in Tests

// tests/login.spec.ts
test('user can log in with valid credentials', async ({ page }) => {
  const loginPage = new LoginPage(page);

  await loginPage.goto();
  await loginPage.login('test@example.com', 'password123');

  expect(await loginPage.isLoggedIn()).toBe(true);
  await expect(page).toHaveURL('/dashboard');
});

test('shows error for invalid credentials', async ({ page }) => {
  const loginPage = new LoginPage(page);

  await loginPage.goto();
  await loginPage.login('test@example.com', 'wrongpassword');

  const error = await loginPage.getErrorMessage();
  expect(error).toContain('Invalid credentials');
});

Benefits visible:

• Test code is readable (domain language)
• Selectors encapsulated (change once, tests still work)
• Actions reusable (login used in multiple tests)

User-Centric Selectors

Select elements the way users find them:

Priority Order (Testing Library Guidance)

// 1. BEST: Accessible selectors (what screen readers see)
page.getByRole('button', { name: 'Submit' });
page.getByRole('heading', { name: 'Welcome' });
page.getByLabel('Email address');

// 2. GOOD: Semantic selectors (visible text)
page.getByText('Click here to continue');
page.getByPlaceholder('Enter your name');
page.getByAltText('Company logo');

// 3. ACCEPTABLE: Test IDs (when no semantic option)
page.locator('[data-testid="checkout-form"]');

// 4. NEVER: Implementation details (brittle)
page.locator('.btn-primary-lg-v2');  // CSS classes
page.locator('div > div > button:nth-child(3)');  // Element hierarchy
page.locator('#component-instance-xyz');  // Internal IDs

Why User-Centric Selectors Matter

Resilience:

• Tests survive refactoring
• CSS changes don't break tests
• Component restructuring doesn't break tests

Accessibility verification:

• If button has no accessible name, test fails
• Forces proper ARIA labels
• Ensures screen reader compatibility

Readability:

• "Click Submit button" not "Click .btn-xyz"
• Tests read like user instructions
• Easier to understand and maintain

Examples

// ❌ BAD: CSS selectors (brittle)
await page.click('.btn-primary.btn-lg');

// ✅ GOOD: Accessible selector (resilient)
await page.click('button[name="submit"]');

// ❌ BAD: Element hierarchy (brittle)
await page.fill('div.form > div:nth-child(2) > input');

// ✅ GOOD: Semantic selector (resilient)
await page.fill('input[name="email"]');
// OR
await page.getByLabel('Email address').fill('test@example.com');

Condition-Based Waiting

Always wait for conditions, not arbitrary times:

The Anti-Pattern

// ❌ BAD: Guessing at timing
await page.click('button');
await page.waitForTimeout(500);  // Hope response in 500ms
const result = await page.textContent('.result');

Problems:

• Flaky tests (fails when slow)
• Slow tests (waits longer than needed)
• No guarantee condition met

The Solution

// ✅ GOOD: Wait for condition
await page.click('button');
await page.waitForSelector('.result');  // Wait until appears
const result = await page.textContent('.result');

// ✅ BETTER: Wait for specific state
await page.click('button');
await page.waitForResponse(resp => resp.url().includes('/api/submit'));
await page.waitForSelector('.result:has-text("Success")');

Framework-Agnostic Waiting

Playwright:

await page.waitForSelector('.element');
await page.waitForResponse(resp => resp.url().includes('/api'));
await page.waitForFunction(() => document.querySelector('.element'));

Selenium:

import { until } from 'selenium-webdriver';
await driver.wait(until.elementLocated(By.css('.element')));
await driver.wait(until.elementIsVisible(element));

Cypress:

cy.get('.element').should('be.visible');  // Built-in retry
cy.intercept('/api/data').as('getData');
cy.wait('@getData');

See: condition-based-waiting skill for comprehensive guidance.

Test Data Management

Use Factories or Fixtures

// ✅ GOOD: Reusable test data factory
async function createTestUser(overrides = {}) {
  return await db.users.create({
    email: `test-${Date.now()}@example.com`,
    password: 'password123',
    name: 'Test User',
    ...overrides
  });
}

// Each test creates its own data
test('user can update profile', async ({ page }) => {
  const user = await createTestUser();

  // ... test using user
  await loginPage.login(user.email, user.password);

  // Cleanup
  await db.users.delete(user.id);
});

Test Isolation

Each test must be independent:

// ✅ GOOD: Each test sets up and tears down
test('test A', async () => {
  const user = await createTestUser();
  // ... test
  await cleanup(user);
});

test('test B', async () => {
  const user = await createTestUser();
  // ... test
  await cleanup(user);
});

// ❌ BAD: Tests share data (flaky)
const sharedUser = await createTestUser();

test('test A', async () => {
  // Uses sharedUser - what if test B modified it?
});

Unique Test Data

// ✅ GOOD: Unique data per test
email: `test-${Date.now()}-${Math.random()}@example.com`

// ✅ GOOD: Use UUIDs
import { randomUUID } from 'crypto';
email: `test-${randomUUID()}@example.com`

Complete E2E Test Structure

Pattern: Arrange-Act-Assert-Cleanup

test('user can complete checkout', async ({ page }) => {
  // ARRANGE: Set up test data
  const user = await createTestUser();
  const product = await createTestProduct();

  // ACT: Perform user workflow
  const loginPage = new LoginPage(page);
  await loginPage.goto();
  await loginPage.login(user.email, user.password);

  const productPage = new ProductPage(page);
  await productPage.goto(product.id);
  await productPage.addToCart();

  const checkoutPage = new CheckoutPage(page);
  await checkoutPage.goto();
  await checkoutPage.fillShippingInfo({
    address: '123 Main St',
    city: 'Seattle',
    zip: '98101'
  });
  await checkoutPage.fillPaymentInfo({
    cardNumber: '4242424242424242',
    expiry: '12/25',
    cvc: '123'
  });
  await checkoutPage.submitOrder();

  // ASSERT: Verify outcome
  await expect(page.locator('[data-testid="order-confirmation"]'))
    .toContainText('Order placed successfully');

  // Verify database state
  const order = await db.orders.findByUserId(user.id);
  expect(order.status).toBe('confirmed');
  expect(order.total).toBe(product.price);

  // CLEANUP: Remove test data
  await db.orders.delete(order.id);
  await db.users.delete(user.id);
  await db.products.delete(product.id);
});

API Mocking (When Needed)

Mock external services, not your own API:

// ✅ GOOD: Mock external payment provider
test('handles payment failure', async ({ page }) => {
  await page.route('https://api.stripe.com/v1/charges', route => {
    route.fulfill({
      status: 400,
      body: JSON.stringify({
        error: { message: 'Card declined' }
      })
    });
  });

  // ... attempt checkout

  await expect(page.locator('[role="alert"]'))
    .toContainText('Payment failed: Card declined');
});

// ❌ BAD: Mocking your own API (defeats purpose)
test('shows user profile', async ({ page }) => {
  await page.route('/api/users/123', route => {
    route.fulfill({ body: JSON.stringify({ name: 'Alice' })});
  });
  // Not testing real API integration!
});

Framework Examples

Playwright (Recommended)

import { test, expect } from '@playwright/test';

test('user signup flow', async ({ page }) => {
  await page.goto('/signup');

  await page.fill('[name="email"]', 'test@example.com');
  await page.fill('[name="password"]', 'password123');
  await page.fill('[name="confirmPassword"]', 'password123');
  await page.click('button[type="submit"]');

  await expect(page).toHaveURL('/verify-email');
  await expect(page.locator('h1')).toContainText('Check your email');
});

Selenium

import { Builder, By, until } from 'selenium-webdriver';

test('user signup flow', async () => {
  const driver = await new Builder().forBrowser('chrome').build();

  try {
    await driver.get('http://localhost:3000/signup');

    await driver.findElement(By.name('email')).sendKeys('test@example.com');
    await driver.findElement(By.name('password')).sendKeys('password123');
    await driver.findElement(By.css('button[type="submit"]')).click();

    await driver.wait(until.urlContains('/verify-email'));
    const heading = await driver.findElement(By.css('h1')).getText();
    expect(heading).toContain('Check your email');
  } finally {
    await driver.quit();
  }
});

Cypress

describe('User signup flow', () => {
  it('allows user to sign up', () => {
    cy.visit('/signup');

    cy.get('[name="email"]').type('test@example.com');
    cy.get('[name="password"]').type('password123');
    cy.get('[name="confirmPassword"]').type('password123');
    cy.get('button[type="submit"]').click();

    cy.url().should('include', '/verify-email');
    cy.get('h1').should('contain', 'Check your email');
  });
});

Mandatory Verification Checklist

BEFORE claiming E2E test complete:

Test Design

• Tests critical user journey (not component behavior)
• Uses Page Object Model (not raw selectors)
• Uses user-centric selectors (accessible roles/labels)
• Waits for conditions (not arbitrary timeouts)
• Test data is unique per test
• Test cleans up after itself

Test Execution

• Test passes consistently (run 10 times)
• Test fails when expected (verify negative cases)
• Test runs in reasonable time (<30 seconds)
• Test doesn't depend on other tests

Test Quality

• Page Objects encapsulate selectors
• Actions have clear domain names
• Tests read like user instructions
• Assertions verify user-visible outcomes

If ANY checkbox unchecked: E2E test is incomplete or incorrect.

Red Flags - STOP IMMEDIATELY

If you catch yourself:

• Writing E2E tests for component behavior
• Testing every edge case at E2E level
• Using CSS class selectors
• Using waitForTimeout() with arbitrary values
• Sharing test data between tests
• Not using Page Objects (raw selectors everywhere)
• E2E tests taking >1 minute each
• E2E tests are >20% of total test suite

THEN:

• STOP immediately
• Consider if E2E is appropriate level
• Use Page Objects and user-centric selectors
• Fix test isolation and waiting issues

E2E Testing with TDD

E2E tests CAN follow TDD, but require incremental approach:

Approach 1: Incremental E2E (Recommended)

Build E2E test one page at a time following TDD:

Iteration 1: Login Page

RED:

test('user can log in', async ({ page }) => {
  await page.goto('/login');
  await page.fill('[name="email"]', 'test@example.com');
  await page.fill('[name="password"]', 'password123');
  await page.click('button[type="submit"]');

  await expect(page).toHaveURL('/dashboard'); // FAILS - login doesn't work
});

GREEN: Implement login page and authentication

REFACTOR: Improve login page code

Iteration 2: Add to Cart

RED:

test('user can add product to cart', async ({ page }) => {
  // Reuse login from iteration 1
  await loginPage.goto();
  await loginPage.login('test@example.com', 'password123');

  // New functionality (RED - doesn't exist yet)
  await page.goto('/product/123');
  await page.click('button[name="add-to-cart"]');

  await expect(page.locator('.cart-badge')).toHaveText('1'); // FAILS
});

GREEN: Implement add to cart functionality

REFACTOR: Improve cart code

Iteration 3-5: Continue incrementally

Approach 2: Skeleton E2E First (Alternative)

Write skeleton E2E test with all steps, expect ALL to fail:

RED:

test('complete checkout flow', async ({ page }) => {
  // Step 1: Login (exists)
  await loginPage.login('test@example.com', 'password123');
  await expect(page).toHaveURL('/dashboard');

  // Step 2: Add to cart (doesn't exist - will fail here)
  await page.goto('/product/123');
  await page.click('button[name="add-to-cart"]');

  // Step 3: Checkout (doesn't exist)
  await page.goto('/checkout');
  await checkoutPage.fillShippingInfo({...});

  // Step 4: Payment (doesn't exist)
  await checkoutPage.fillPaymentInfo({...});
  await checkoutPage.submitOrder();

  // Step 5: Confirmation (doesn't exist)
  await expect(page.locator('.order-confirmation')).toBeVisible();
});

Run test: FAILS at step 2 (add to cart doesn't exist)

GREEN: Implement add to cart Run test: FAILS at step 3 (checkout doesn't exist)

GREEN: Implement checkout Run test: FAILS at step 4 (payment doesn't exist)

... continue until all steps implemented

When to use each approach:

• Incremental: When iterating rapidly, want fast feedback
• Skeleton: When have complete flow spec, want to track overall progress

Both approaches follow TDD: Write test, watch fail, implement, watch pass.

Cross-reference: See test-driven-development skill for core RED-GREEN-REFACTOR principles.

Integration with Other Skills

Combines with:

• test-driven-development: Write E2E test BEFORE implementing flow (see E2E TDD section above)
• condition-based-waiting: Wait for conditions, not time
• verification-before-completion: E2E tests required for critical flows
• frontend-component-testing: Use component tests for most UI testing
• frontend-accessibility-verification: E2E tests verify accessible selectors

Testing Pyramid Guidance

Modern frontend testing distribution:

       /\
      /E2E\       10-15% - Critical journeys only
     /------\
    /Integration\  40-50% - Highest ROI
   /------------\
  /  Component  \  30-40% - User behavior
 /--------------\
/     Unit      \  5-10% - Pure logic
/----------------\

E2E tests should be the SMALLEST portion of your test suite.

Common Rationalizations

Example Session

Agent: "I'm implementing user checkout flow."

[Uses frontend-e2e-user-journeys skill]

1. Determine if E2E appropriate:
   - Complete workflow? YES (add to cart → checkout → payment)
   - Business critical? YES (checkout is revenue-critical)
   - Could be component test? NO (spans multiple pages)
   → E2E test appropriate

2. Create Page Objects:
   - ProductPage (for adding to cart)
   - CheckoutPage (for checkout form)
   - ConfirmationPage (for order confirmation)

3. Write E2E test with TDD:
   - RED: Write test expecting checkout flow works
   - GREEN: Implement checkout flow
   - REFACTOR: Improve code, E2E test catches regressions

4. Use user-centric selectors:
   - button[name="add-to-cart"]
   - input[name="cardNumber"]
   - [role="alert"] (for error messages)

5. Wait for conditions:
   - waitForResponse('/api/checkout')
   - waitForSelector('[data-testid="confirmation"]')

6. Test isolation:
   - Create unique test user
   - Create unique test product
   - Clean up after test

7. Verify test:
   - Runs in <30s
   - Passes 10 times consecutively
   - Fails when expected (invalid card)

"Checkout E2E test complete. Critical user journey verified."

References

• Page Object Model: Industry standard pattern
• Testing Library philosophy: User-centric testing
• Playwright: Built-in support for E2E testing
• condition-based-waiting skill: Comprehensive waiting guidance

Remember: E2E TESTS ONLY FOR CRITICAL USER JOURNEYS. Use component tests for most UI testing.