End-to-End testing with Cypress.js

End-to-End testing with Cypress.js

End-to-End (E2E) testing is the cornerstone of delivering reliable and high-quality software. It represents the final barricade that ensures bugs and issues are caught before your product reaches the end user. According to a report by the Consortium for IT Software Quality, poor software quality costs US companies alone approximately $2.08 trillion in 2020. A large portion of these costs can be attributed to software failures that could have been discovered through comprehensive E2E testing.

Equip yourself with the knowledge and skills necessary to conduct effective E2E testing with our deep dive into Cypress.js, a powerful tool for E2E testing. Don't miss out on this opportunity to become a master of E2E testing – continue reading our guide packed with insights and valuable know-how!

1. General overview of Cypress.js

Cypress.js is an end-to-end testing framework built for the web. Developed to simplify the process of setting up, writing, running, and debugging tests, it's designed to work out of the box.

The primary features of Cypress.js include:?

  • real-time reloading,?
  • automatic waiting,?
  • network traffic control,?
  • simultaneous testing.?

It offers a neat, interactive UI for running tests, and its real-time reloading feature ensures tests are automatically rerun whenever the test files are saved. Cypress.js even lets you control and manage all network requests from your application, giving you complete control over your testing environment.

Compared to popular testing tools like Selenium, Cypress.js stands out with features like real-time reloading and automatic waiting. Unlike Selenium, which requires third-party plugins for features like screenshots and parallel execution, Cypress.js provides these features out-of-the-box.

Feature

Cypress.js

Selenium

Real-time reloading

Yes

No

Automatic waiting

Yes

No

Screenshots & Video recording

Out-of-the-box

Via third-party plugins

Parallel execution

Yes

Via third-party plugins

As for the advantages of Cypress.js, it has a straightforward setup, offers real-time feedback, performs automatic waiting, and allows for network stubbing. However, it also comes with some drawbacks, such as only supporting JavaScript and presently providing support for Chrome-based browsers only.

Advantages

Disadvantages

  1. Straightforward setup
  2. Real-time feedback
  3. Automatic waiting
  4. Network stubbing

  1. Only supports JavaScript
  2. Limited to Chrome-based browsers

2. How to install and set up Cypress.js?

To install Cypress.js, you need to have Node.js installed on your machine. If you haven't installed it yet, download Node.js and follow the installation instructions.

Next, navigate to your project's root directory in the terminal, and run the following command to install Cypress via npm:

npm install cypress --save-dev

This command installs Cypress locally as a dev dependency for your project.

Once installed, you can open Cypress by running:

npx cypress open

On first launch, Cypress will create examples of a complete structure for your test files in cypress/integration/.

The Cypress interface will also open, showing the existing test files. You can run the tests by clicking on the test file's name.

Once you've installed Cypress, you can configure it to suit your needs. Cypress comes with a default configuration that you can modify according to your requirements.

The configuration file, cypress.json, is located in your project's root directory. It is automatically created when you run Cypress for the first time.

Here's an example of what it looks like:

{

??"baseUrl": "https://localhost:8080",

??"integrationFolder": "cypress/e2e",

??"testFiles": "**/*.test.js"

}

  • baseUrl: This is the URL that Cypress will use as a prefix when using cy.visit or cy.request commands.
  • integrationFolder: This is the folder where Cypress will look for the test files.
  • testFiles: The pattern that Cypress uses to locate test files in the integration folder.

You can modify these settings and add more based on the Cypress Configuration guide.

3. Creating and Running Your First End-to-End Test Using Cypress.js

After setting up Cypress.js, you're now ready to create your very first E2E test. Let's walk through the process.

  1. Test Scenario Creation

Start by outlining the scenario you'd like to test. For this instance, let's consider a simple login function on a web application.

  1. Writing the Test using Cypress.js API

Navigate to the cypress/integration directory, and create a new file named login.spec.js. Here's a basic implementation of our test scenario:

describe('Login Test', function() {

????it('Logs in to the application', function() {

????????cy.visit('/login') // Visit login URL

????????cy.get('input[name=username]').type('testuser') // Enter username

????????cy.get('input[name=password]').type('password123') // Enter password

????????cy.get('button[type=submit]').click() // Click submit button

????????cy.url().should('include', '/dashboard') // Verify that URL includes '/dashboard'

????})

})

In the above script, we're using several Cypress commands:

  • cy.visit(): This command is used to visit the specified URL.
  • cy.get(): Used to get a DOM element by selector.
  • cy.type(): This command types the specified text into the selected input field.
  • cy.click(): This command clicks the selected button.
  • cy.url(), cy.should(), and 'include': These commands are used to assert that the URL includes '/dashboard'.

  1. Interacting with User Interface Elements

The cy.get() command is used to query DOM elements and interact with them. In our test, we're using .type() to type into input fields, and .click() to click a button.

You can interact with various types of elements, such as:

  • Input: For text fields, use the .type() command to enter text: cy.get('input[name=fieldName]').type('Your Text')
  • Button: For buttons, use the .click() command: cy.get('button[type=submit]').click()
  • Checkbox: For checkboxes, use the .check() command to select them: cy.get('input[name=checkboxName]').check()

This is a simple example of creating an E2E test with Cypress.js, but Cypress.js is capable of much more complex scenarios and interactions.

4. Testing Asynchronous Behavior and Network Requests with Cypress.js

Asynchronous operations are a fundamental part of modern web applications. Cypress.js stands out in dealing with async behavior due to its automatic waiting mechanism.

Handling Asynchrony in Cypress.js

Cypress automatically waits for the DOM to load, for animations to complete, for Ajax calls to resolve, and much more. You typically won't need to add waits or sleep to your tests. For instance, if you're testing form submission that makes an API call, you simply write the sequence of actions, and Cypress will automatically wait for the responses before moving on to other commands.

cy.get('form').submit()

cy.get('.success-message').should('be.visible')

In the above code, Cypress will not execute the second line until the form submission, which is usually an asynchronous action, is completed.

Controlling and Asserting Network Requests

Cypress allows you to stub network requests or listen to them via cy.route() command. This feature enables you to control the behavior of your application under test, by manipulating responses or by asserting the requests your application makes.

cy.server()

cy.route('POST', '/users', {id: 1, name: 'New User'}) // Stubbing a response

cy.visit('/users/new')

cy.get('form').submit()

cy.get('.success-message').should('be.visible')

5. Developing an E2E Test Scenario with Cypress.js

Let's go through the process of developing and implementing a realistic E2E test scenario. Suppose we're testing a user login functionality.

Developing a Test Scenario

?First we should outline the steps a user would typically follow to log into an application:

  1. Visit the login page.
  2. Enter username and password.
  3. Click on the login button.
  4. Verify that we've been redirected to the dashboard.
  5. Check the username on the dashboard.

Implementing the Scenario with Cypress.js

Now, let's turn these steps into a Cypress test:

describe('User Login', function() {

????it('Logs into the application', function() {

????????cy.visit('/login')

????????cy.get('input[name=username]').type('testuser')

????????cy.get('input[name=password]').type('password123')

????????cy.get('button[type=submit]').click()

????????cy.url().should('include', '/dashboard')

????????cy.get('.username').should('contain', 'testuser')

????})

})

In this test, we're using a .should() command to assert that the URL includes '/dashboard' and that the username displayed on the dashboard is the one we used to login. This is a straightforward E2E test for a typical user login flow.

Conclusion

By utilizing a comprehensive tool such as Cypress.js for E2E testing, potential software failures can be identified and rectified before they reach the end-user. This leads to enhanced user experience and satisfaction.

Our guide has provided you with the understanding of Cypress.js functionalities, installation and setup, the creation of E2E tests, and working with asynchronous behaviors. Armed with this knowledge, you'll be well-equipped to develop your own robust E2E testing scenarios, uphold the quality of your software, and ultimately prevent costly software errors.

Remember, effective testing is an iterative process that requires practice and continuous improvement. So keep learning, keep testing, and keep improving!

And if you need professional E2E testing right now, apply to Cherish DEV. Our experienced QA Engineers will increase the quality of your software to maximum quickly, transparently and for a reasonable price. Contact us!

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