Automating APIs with Cypress: The Ultimate Guide

API testing is an essential part of modern software development, ensuring that backend services function correctly and efficiently. While Cypress is primarily known for UI testing, it also provides powerful capabilities for API testing through its built-in cy.request() command. With Cypress, we can perform HTTP requests, handle authentication, validate response data, and integrate seamlessly with UI tests.

This blog will explore how to write API test scripts using Cypress, handle authentication, make assertions, and leverage useful plugins to enhance API testing.

Write API Test Scripts:

Cypress doesn’t provide direct API testing capabilities, but we can use Cypress commands and plugins to make API requests and assertions. We can write your API test scripts in the integration test files provided by Cypress. example:

describe('API Testing', () => {
 it('GET Request', () => {
 cy.request('GET', 'https://api.example.com/posts')
 .then((response) => {
 expect(response.status).to.eq(200);
 expect(response.body).to.have.property('data');
 });
 });
it('POST Request', () => {
 cy.request('POST', 'https://api.example.com/posts', { title: 'New Post' })
 .then((response) => {
 expect(response.status).to.eq(201);
 expect(response.body).to.have.property('id');
 });
 });
});

Handling Authentication

If your API endpoints require authentication, we can handle it using the cy.request command by adding headers, tokens, or authentication credentials.

cy.request({
 method: 'POST',
 url: 'https://api.example.com/auth',
 body: {
 username: 'username',
 password: 'password',
 },
}).then((response) => {
 const authToken = response.body.token;
cy.request({
 method: 'GET',
 url: 'https://api.example.com/secure-data',
 headers: {
 Authorization: `Bearer ${authToken}`,
 },
 }).then((secureResponse) => {
 expect(secureResponse.status).to.eq(200);
 });
});

Assertions

Use Cypress assertion methods expect to verify the API responses and ensure they meet your expectations. We can check response status codes, response body, and specific data fields.

it('GET Request', () => {
 cy.request('GET', 'https://api.example.com/posts')
 .then((response) => {
 expect(response.status).to.eq(200);
 expect(response.body).to.have.property('data');
});

Plugins

Cypress provides the flexibility to use plugins for more testing features. For eg. we can use libraries like cypress-wait-until to wait for certain conditions to be met in the API response.

Conclusion

Cypress API testing offers several benefits, such as easy setup, real-time debugging, automatic waiting, and seamless integration with UI tests. It is beneficial to integrate Cypress with other API testing tools like Postman or RestAssured.