Cypress #
Cypress is a powerful end-to-end testing framework designed for modern web applications. It enables developers to write and run tests directly in the browser, providing a real-time view of the application’s behavior. Below is a basic overview of using Cypress in a Node.js application:
Installation: #
Install Cypress as a development dependency:
npm install --save-dev cypress
Opening Cypress: #
After installation, open Cypress using the command:
npx cypress open
This opens the Cypress Test Runner, where you can write and execute tests.
Writing Your First Test: #
Create a new test file (e.g., cypress/integration/sample_spec.js):
describe('My First Test', () => {
it('Visits the homepage', () => {
cy.visit('/');
cy.contains('Welcome to My App');
});
});
This test visits the root URL and asserts that the page contains the text ‘Welcome to My App’.
Running Tests: #
Run your Cypress tests using the command:
npx cypress run
This runs tests in headless mode and provides command-line results.
Interactive Test Execution: #
Use the Cypress Test Runner for interactive test execution:
npx cypress open
This opens the Cypress Test Runner, allowing you to interactively run and debug tests.
Assertions and Commands: #
Cypress provides a rich set of assertions and commands for interacting with the application:
cy.get('.login-form').should('be.visible');
cy.get('#username').type('john_doe');
cy.get('#password').type('password123');
cy.get('button[type="submit"]').click();
Here, Cypress asserts the visibility of a login form, types into input fields, and clicks on a submit button.
Custom Commands: #
Define custom commands for reusable test steps:
// cypress/support/commands.js
Cypress.Commands.add('login', (username, password) => {
cy.get('#username').type(username);
cy.get('#password').type(password);
cy.get('button[type="submit"]').click();
});
// In your test
cy.login('john_doe', 'password123');
Handling Asynchronous Operations: #
Cypress automatically waits for elements to appear and resolves promises:
cy.get('.loading-spinner').should('not.exist');
Cypress waits until the loading spinner is not visible before proceeding.
Network Requests and Stubbing: #
Intercept and stub network requests for testing different scenarios:
cy.intercept('GET', '/api/data', { fixture: 'sample-data.json' }).as('getData');
cy.visit('/');
cy.wait('@getData');
This intercepts a GET request to ‘/api/data’ and responds with the data from a fixture file.
Running Tests in Different Browsers: #
Run tests in different browsers using Cypress:
npx cypress run --browser chrome
Cypress supports multiple browsers for cross-browser testing.
Cypress revolutionizes end-to-end testing by providing a developer-friendly and powerful framework. Its real-time view, automatic waits, and comprehensive command set make it an excellent choice for testing modern web applications. Whether running tests in headless mode for continuous integration or interactively in the Cypress Test Runner, Cypress simplifies the testing process and enhances the reliability of web applications.