End To End Testing With Cypress | Testing

Using Cypress for end-to-end testing

End-to-end (E2E) testing simulates real user interactions to test the entire application flow. Cypress is a powerful E2E testing framework for JavaScript applications that provides a robust and user-friendly interface for writing and running tests.

Key Points:

Cypress is a powerful and user-friendly E2E testing framework for JavaScript applications.
E2E testing simulates real user interactions to ensure the entire application flow works correctly.
Cypress provides a robust API for writing tests and a user-friendly interface for running them.

Setting Up Cypress

To get started with Cypress, you need to install it as a development dependency in your project.


// Install Cypress
npm install --save-dev cypress

// Add Cypress scripts to package.json
{
  "scripts": {
    "cypress:open": "cypress open",
    "cypress:run": "cypress run"
  }
}

// Open Cypress test runner
npm run cypress:open

Writing E2E Tests

Writing E2E tests with Cypress involves using its powerful API to simulate user interactions and verify application behavior.


// Example of an E2E test with Cypress
// cypress/integration/sample_spec.js
describe('My First Test', () => {
  it('Visits the app and checks the title', () => {
    cy.visit('http://localhost:3000');
    cy.contains('h1', 'Welcome to React');
  });

  it('Increments the counter', () => {
    cy.visit('http://localhost:3000');
    cy.contains('button', 'Increment').click();
    cy.contains('p', 'Count: 1');
  });
});

Running E2E Tests

To run your E2E tests, you can use the Cypress test runner or run the tests in the terminal.


// Open Cypress test runner
npm run cypress:open

// Run Cypress tests in the terminal
npm run cypress:run

Testing Forms and User Inputs

Cypress makes it easy to test forms and user inputs by simulating typing and form submission.


// Example of testing forms and user inputs with Cypress
// cypress/integration/form_spec.js
describe('Form Test', () => {
  it('Fills and submits the form', () => {
    cy.visit('http://localhost:3000/form');
    cy.get('input[name="username"]').type('testuser');
    cy.get('input[name="password"]').type('password123');
    cy.get('form').submit();
    cy.contains('p', 'Form submitted');
  });
});

Mocking API Calls

Cypress allows you to mock API calls to test how your application handles different responses.


// Example of mocking API calls with Cypress
// cypress/integration/api_spec.js
describe('API Test', () => {
  it('Mocks API response', () => {
    cy.server();
    cy.route('GET', '/api/data', { data: 'mock data' }).as('getData');
    cy.visit('http://localhost:3000');
    cy.wait('@getData');
    cy.contains('p', 'Data: mock data');
  });
});

Using Cypress Plugins

Cypress supports a variety of plugins that can extend its functionality, such as handling iframes, improving accessibility testing, and more.


// Example of using a Cypress plugin
// Install Cypress axe for accessibility testing
npm install --save-dev cypress-axe

// cypress/plugins/index.js
module.exports = (on, config) => {
  require('cypress-axe')(on, config);
};

// cypress/integration/accessibility_spec.js
describe('Accessibility Test', () => {
  it('Checks accessibility', () => {
    cy.visit('http://localhost:3000');
    cy.injectAxe();
    cy.checkA11y();
  });
});

Summary

In this tutorial, you learned about using Cypress for end-to-end testing in React applications. Cypress provides a powerful and user-friendly interface for writing and running tests that simulate real user interactions. By setting up Cypress, writing E2E tests, and utilizing its API for testing forms, user inputs, and mocking API calls, you can ensure that your React application works as expected from end to end.

React - End-to-End Testing with Cypress