Cypress

Setup

On first use, read setup.md for integration guidelines.

When to Use

User needs E2E tests, component tests, or API tests with Cypress. Agent writes tests, debugs flaky specs, configures CI/CD, and creates custom commands.

Architecture

Project tests live in the standard Cypress structure:

cypress/
├── e2e/              # E2E test specs
├── component/        # Component tests (if enabled)
├── fixtures/         # Test data JSON files
├── support/
│   ├── commands.ts   # Custom commands
│   ├── e2e.ts        # E2E support file
│   └── component.ts  # Component support file
└── downloads/        # Downloaded files during tests
cypress.config.ts     # Main configuration

Quick Reference

Topic	File
Setup process	setup.md
Memory template	memory-template.md
Selectors & queries	selectors.md
Custom commands	commands.md
Network & API	network.md
CI/CD configuration	ci.md

Core Rules

1. Selectors: data-testid First

// ✅ Resilient — survives refactors
cy.get('[data-testid="submit-btn"]')
cy.get('[data-cy="user-list"]')

// ❌ Fragile — breaks on style/structure changes
cy.get('.btn-primary.submit')
cy.get('#root > div > form > button:nth-child(3)')
cy.get('button').contains('Submit')  // OK for text, not structure

Priority order: data-testid > data-cy > aria-* > text content > CSS selectors.

2. Never Use Fixed Waits

// ❌ Flaky and slow
cy.wait(3000)
cy.get('.loader').should('exist')
cy.wait(2000)

// ✅ Wait for actual state
cy.get('.loader').should('not.exist')
cy.get('[data-testid="results"]').should('be.visible')
cy.intercept('GET', '/api/users').as('getUsers')
cy.wait('@getUsers')

3. Intercept Network Requests

// Setup intercepts BEFORE triggering actions
cy.intercept('POST', '/api/login', { statusCode: 200, body: { token: 'abc' } }).as('login')
cy.get('[data-testid="login-btn"]').click()
cy.wait('@login')

4. One Assertion Focus per Test

// ✅ Clear failure message
it('shows error on invalid email', () => {
  cy.get('[data-testid="email"]').type('invalid')
  cy.get('[data-testid="submit"]').click()
  cy.get('[data-testid="email-error"]').should('contain', 'Valid email required')
})

// ❌ Multiple concerns — unclear which failed
it('validates the entire form', () => {
  // Tests 5 different validation rules
})

5. Commands for Repeated Actions

// cypress/support/commands.ts
Cypress.Commands.add('login', (email: string, password: string) => {
  cy.session([email, password], () => {
    cy.visit('/login')
    cy.get('[data-testid="email"]').type(email)
    cy.get('[data-testid="password"]').type(password)
    cy.get('[data-testid="submit"]').click()
    cy.url().should('include', '/dashboard')
  })
})

// Usage
cy.login('user@example.com', 'password123')

6. Fixtures for Test Data

// cypress/fixtures/user.json
{
  "validUser": { "email": "test@example.com", "password": "Test123!" },
  "adminUser": { "email": "admin@example.com", "password": "Admin123!" }
}

cy.fixture('user').then((users) => {
  cy.login(users.validUser.email, users.validUser.password)
})

7. Isolation: Reset State Before Tests

beforeEach(() => {
  cy.intercept('GET', '/api/notifications', { body: [] })
  cy.clearCookies()
  cy.clearLocalStorage()
  // Or: cy.task('db:seed') if using database reset
})

Common Traps

Trap	Consequence	Fix
cy.wait(ms) fixed delays	Flaky tests, slow CI	Use cy.intercept().as() + cy.wait('@alias')
CSS selectors for actions	Break on redesign	Use data-testid attributes
Test interdependence	One failure cascades	Each test must setup its own state
Asserting too early	False positives	Chain .should() to auto-retry
Forgetting baseUrl	Hardcoded URLs everywhere	Set baseUrl in config
Skipping viewport tests	Mobile bugs in prod	Add cy.viewport() tests
Ignoring retry-ability	Flaky assertions	Use Cypress queries, not jQuery

Debugging

Time Travel

Click any command in the Command Log to see DOM snapshot at that moment.

Pause and Step

cy.get('[data-testid="item"]').then(($el) => {
  debugger  // Opens DevTools
})
// Or
cy.pause()  // Pause execution, step manually

Console Debugging

cy.get('[data-testid="items"]')
  .should('have.length.gt', 0)
  .then(($items) => {
    console.log('Found items:', $items.length)
  })

Configuration

cypress.config.ts Essentials

import { defineConfig } from 'cypress'

export default defineConfig({
  e2e: {
    baseUrl: 'http://localhost:3000',
    viewportWidth: 1280,
    viewportHeight: 720,
    defaultCommandTimeout: 10000,
    requestTimeout: 10000,
    retries: { runMode: 2, openMode: 0 },
    video: false,  // Enable for CI debugging
    screenshotOnRunFailure: true,
    setupNodeEvents(on, config) {
      // Plugins here
    },
  },
  component: {
    devServer: {
      framework: 'react',  // or 'vue', 'angular', etc.
      bundler: 'vite',     // or 'webpack'
    },
  },
})

TypeScript Support

// cypress/support/commands.ts
declare global {
  namespace Cypress {
    interface Chainable {
      login(email: string, password: string): Chainable<void>
      getByTestId(testId: string): Chainable<JQuery<HTMLElement>>
    }
  }
}

Cypress.Commands.add('getByTestId', (testId: string) => {
  return cy.get(`[data-testid="${testId}"]`)
})

Running Tests

Command	Purpose
npx cypress open	Interactive mode
npx cypress run	Headless (CI)
npx cypress run --spec "cypress/e2e/login.cy.ts"	Single spec
npx cypress run --headed	Headless but visible
npx cypress run --browser chrome	Specific browser

External Endpoints

This skill does not call external APIs. Cypress runs entirely locally or in your own CI environment.

Security & Privacy

Data that stays local:

• All test code and fixtures remain in project directory
• Cypress runs locally or in your own CI environment

This skill does NOT:

• Send data to external services
• Require API keys or authentication
• Access files outside project directory

Note: Cypress Cloud (optional, paid) can receive test results if configured with CYPRESS_RECORD_KEY. This skill does not configure or recommend it.

Related Skills

Install with clawhub install <slug> if user confirms:

• playwright — alternative E2E framework
• typescript — TypeScript best practices
• javascript — JS fundamentals and patterns
• react — React component testing

Feedback

• If useful: clawhub star cypress
• Stay updated: clawhub sync