Ecom Cypress Tests

E2E Tests with Cypress teaches you how to perform end-to-end (E2E) testing using Cypress, one of the most popular tools for automated testing in JavaScript, especially for web applications. I will explain all the concepts and steps in detail.

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What are E2E Tests?

End-to-End Tests (E2E) are automated tests that verify the complete behavior of an application, from start to finish, simulating user interaction with the interface. These tests are important because they validate that all parts of the application work correctly together, as expected, in a real environment.

Cypress: What is it and How Does It Work?

Cypress is a tool for automated testing of web applications. It is designed to be easy to use, powerful and fast. It allows you to write tests that interact with the application's user interface in the same way a user would, clicking buttons, filling out forms, validating texts, and much more.

Some important features of Cypress:

• Real-time tests: It runs the tests in the browser itself, allowing you to see the tests running live.
• Ease of setup: No complicated setup required to get started.
• Fast execution: Since Cypress runs in the browser, test execution is faster compared to other E2E testing tools.
• CI/CD Integration: It easily integrates with CI/CD pipelines for test automation.

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Module 34 Walkthrough

1. Conceptualizing the Cypress tool

Cypress is an automated testing tool for web applications, mainly for E2E testing. It is designed to interact directly with application code in the browser, making testing more efficient.

2. Installing Cypress on the machine

To start using Cypress, you need to install it in your project. Here is the installation command:

npm install cypress --save-dev

This will install Cypress as a development dependency in your project.

3. Starting Cypress

After installing Cypress, you can open it using the following command in the terminal:

npm install cypress --save-dev

This will open the Cypress Test Runner where you can see the tests running in the browser. It also creates a cypress folder in your project, where all tests and configurations are stored.

4. Using the describe function to group tests

In Cypress (and Jest), we use describe to group multiple tests that are part of the same suite or module. This helps to organize the tests in a more structured way.

npx cypress open

In the example above:

• describe is used to group login related tests.
• it defines a specific test within the group. What follows inside it is the code that performs the verification (test steps).

5. Using the it function

The it function is used to define individual test cases. Each test case must be independent and represent a specific functionality or behavior of the application.

6. Retrieving elements with the cy.get function

The cy.get function is used to select page elements to interact with in tests.

Example:

describe('Teste de Login', () => {
  it('Deve realizar o login com sucesso', () => {
    cy.visit('https://exemplo.com/login');
    cy.get('input[name="username"]').type('usuario');
    cy.get('input[name="password"]').type('senha123');
    cy.get('button[type="submit"]').click();
    cy.url().should('include', '/dashboard');
  });
});

Here, cy.get searches for the input with name="username" and the submit button with type="submit", and then performs the actions of type and click.

7. Introduction to VScode and Autocomplete

You can use VSCode to edit your tests and take advantage of Cypress autocomplete, which makes it easy to write tests correctly by suggesting methods and commands as you type.

8. Using Hierarchical Relationships

Cypress allows you to select elements based on the page hierarchy, using more complex CSS selectors. For example, you can select a button that is inside a div with a specific class:

cy.get('input[name="username"]').type('usuario');
cy.get('button[type="submit"]').click();

9. Building Filtering Tests

An example of a filtering test would be to check whether, when applying a filter, the list of items is updated correctly. Cypress allows you to perform this type of test easily, interacting with the filters and checking the results.

cy.get('.modal').find('button').click(); // Encontra o botão dentro de .modal e clica

10. Using the beforeEach function

The beforeEach function is useful for configuring the application state before each test. This is especially important when you need to ensure that the application is in an initial state before running the test.

npm install cypress --save-dev

11. Knowing Cypress Return Type

Cypress uses Promises to manage asynchronous time, but it automatically handles these promises, making testing simpler. It is not necessary to use await or .then() in many cases as Cypress handles this internally.

12. Organizing the Code to Reduce Lines

Keeping tests organized and reusable is essential. You can create helper functions and reuse code snippets.

Example:

npx cypress open

13. Knowing Additional Features of Cypress

• Take Screenshots: Cypress can automatically take screenshots during testing. This helps you visualize what happened when a test failed.

describe('Teste de Login', () => {
  it('Deve realizar o login com sucesso', () => {
    cy.visit('https://exemplo.com/login');
    cy.get('input[name="username"]').type('usuario');
    cy.get('input[name="password"]').type('senha123');
    cy.get('button[type="submit"]').click();
    cy.url().should('include', '/dashboard');
  });
});

• Generate Reports: Cypress allows you to generate test execution reports, which makes it easier to analyze the results.

• Cypress Run: To run the tests in headless mode (without a graphical interface), use the command:
  

cy.get('input[name="username"]').type('usuario');
cy.get('button[type="submit"]').click();

• HTTP Request Mocking: You can simulate server responses with Cypress, without having to make real calls. This is useful for testing scenarios with specific data.

cy.get('.modal').find('button').click(); // Encontra o botão dentro de .modal e clica

14. Mock Service Worker (MSW) Installation

Mock Service Worker is a tool that allows you to intercept HTTP requests in your tests. It can be used with Cypress to simulate requests and control responses.

cy.get('.filter').select('Option 1');
cy.get('.item-list').should('have.length', 5);

Then you can configure network handlers to intercept the requests.

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Conclusion

In Module 34, you learned how to use Cypress to perform E2E tests on your application, ensuring that it works correctly in real use situations. You learned how to configure Cypress, write tests, interact with page elements, and use features like beforeEach, cy.get, screenshots, reports, and much more. These tests are crucial to ensure that your application works correctly and that new bugs are not introduced.

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