Cypress Best Practices: Test Automation Guide

Selecting the right tool and adhering to best practices is paramount for achieving efficient and effective testing processes. One tool that has gained significant popularity among developers and quality assurance professionals is Cypress.

In this comprehensive guide, we will delve into the service, explore its advantages and disadvantages, and outline best practices for harnessing its full potential in your test automation endeavors.

Cypress Best Practices - Basics

Cypress is an open-source JavaScript e2e testing framework designed for modern web applications. The automation tool operates directly within the browser, allowing developers to write test cases with real-time feedback.

It provides a robust set of capabilities for performing tasks such as interacting with web elements, simulating user actions, and making assertions about the application's behavior. After local installation you can perform one of the common testing scenarios: checking login page functionality.

Check also our Cypress Cheat Sheet.

Cypress is a cutting-edge front-end testing tool that has rapidly gained popularity for its ability to streamline and enhance the process of conducting comprehensive tests on web applications.

It provides a robust environment for creating and running testing suites, making it an indispensable tool for modern software development teams. Here, we'll delve into the world of Cypress and explore key concepts and best practices associated with it.

- Test Suites and Test Cases:

Cypress enables developers to organize their testing efforts effectively through the use of test suites and test cases. A test suite refers to a collection of related test cases, and each test case is an individual test. Cypress excels at running both unit testing and end-to-end (E2E) testing scenarios.

- Running Tests:

Using Cypress, you can execute tests in a controlled manner. It provides a user-friendly Cypress runner that allows you to initiate and manage test runs with ease. You can interact with the test cases using the UI, overseeing the progress of every test case.

- Defining Tests:

Defining a test in Cypress is straightforward. You can use the it function to specify each test case within your test code. These tests are typically organized into separate test specs to ensure isolation and clarity in your testing efforts.

- Cypress Cloud:

Cypress offers a cloud-based solution called Cypress Cloud, which facilitates running and managing tests in a distributed environment. This is particularly useful when you have a large number of test cases, such as 10 test cases or more, and you want to leverage the power of cloud resources to speed up testing.

- Test Data and Assertions:

When writing tests in Cypress, it's important to include test data and assertions to guard Cypress from proceeding until an explicit condition is met. This helps ensure that your tests accurately reflect the state of your application and produce reliable results.

Advantages of Using Cypress

1. Real-Time Debugging

Cypress offers real-time debugging capabilities, enabling developers to pause test execution, inspect the application's state, and troubleshoot issues directly from the browser. This feature greatly expedites the debugging process and enhances productivity.

2. Automatic Waiting

One of Cypress's standout features is its automatic waiting. It intelligently waits for elements to become interactive or visible before executing actions, eliminating the need for manual timeouts and ensuring test stability.

3. Interactive Test Runner

Cypress provides an interactive test runner that displays the application in one pane and the test's commands and assertions in another. This split-screen view facilitates real-time validation and aids in identifying issues quickly.

4. Consistent and Reliable Tests

With Cypress, you can write consistent and reliable tests due to its automatic retries and assertions. Tests automatically retry failed commands, reducing false negatives and improving test stability.

5. Seamless Integrations

Cypress seamlessly integrates with various Continuous Integration (CI) tools, making it easy to incorporate automated tests into your CI/CD pipeline. It supports platforms like Travis CI, CircleCI, Jenkins, Github and more.

Disadvantages of Using Cypress

While Cypress offers numerous advantages, it's essential to consider its limitations:

1. Limited Browser Support

Cypress primarily supports Chromium-based browsers, which may limit its compatibility with applications that require testing across a wide range of browsers.

2. No Cross-Domain Testing

Due to browser security restrictions, Cypress cannot test applications across different domains in a single test. This limitation can be challenging when working with complex web ecosystems.

3. No Support for Native Mobile Apps

Cypress is focused on web application testing and does not support testing of native mobile applications, unlike some other testing tools.

Cypress Best Practices You Need for Testing

1. Stay Organized!

Organizing your tests is crucial for maintaining a scalable and maintainable test suite. Avoid sharing page objects, as this can lead to code duplication and brittle tests. Instead, write test specs in isolation, ensuring that every test case is self-contained and does not rely on the state left by previous tests.

Additionally, avoid using the application's UI to log in during tests. Instead, programmatically log into your application using API calls or other methods. This approach ensures that your tests are not dependent on the login process and can run independently.

2. Run Tests Intelligently

As your test suite expands and its execution time increases, you might encounter issues in the CI system. You should integrate your version control system with your test suite in a way that prevents merges until all your tests have successfully passed. However, it's important to acknowledge that this approach can result in longer test execution times, which can slow down the process of merging branches and delivering new features. This issue can become even more pronounced when you have chains of dependent branches awaiting merging.

One effective solution to mitigate this problem is to implement Smart Orchestration through Cypress Cloud. Smart Orchestration leverages a combination of parallelization, load balancing, Auto Cancellation, and Spec Prioritization to optimize your available computing resources and minimize resource wastage.

This approach enables you to maintain a high level of efficiency in your testing processes while accommodating the scaling demands of a growing test suite.

3. Select Elements with Data-* Attributes

When selecting elements for your tests, avoid using selectors based on CSS attributes such as id, class, or tag, as they are prone to changes. Instead, use data-* attributes to provide context to your selectors. Elements with data-* attributes are more stable and less likely to break when the application's styling or behavior changes.

4. Don't Start Your Back End Web Server From Within Cypress

Every command executed through cy.exec() or cy.task() must eventually terminate; otherwise, Cypress will be unable to proceed with any other commands.

Attempting to launch a web server using cy.exec() or cy.task() introduces a range of complications due to the following reasons:

1. You must background the process.
2. You lose the ability to interact with it through the terminal.
3. Access to its standard output (stdout) or logs becomes unavailable.
4. You need to handle the intricacies of starting an already running web server every time your tests run.
5. Frequent port conflicts are likely to arise.

As for shutting down the process in an after hook, it's not a reliable solution because there is no assurance that code within an after hook will always execute. In the Test Runner, you can restart or refresh the environment during a test, which can prevent the code in an after hook from running when such interruptions occur.

5. Use Cypress Testing Library

Cypress works well with the Testing Library project, which promotes writing tests that resemble how users interact with your application. You can use library package to access familiar testing library methods for selecting elements in Cypress specs. This aligns with best practices for user-centered testing.

6. Use Aliases and Closures to Access and Store what Commands Yield You.

Cypress commands are asynchronous and do not return values that you can assign with const, let, or var. Instead, use aliases and closures to access and store the values or elements returned by Cypress commands. This ensures that you work with the correct values during test execution.

7. Only Test Websites That You Control

Use cy.request() to communicate with 3rd-party servers via their APIs, if necessary.

When you need to run a test, focus on testing websites and servers that you control. Avoid attempting to interact with or test third-party websites or services, as this can lead to various issues, including time-consuming tests and potential blocks or bans.

If you must interact with third-party services, consider using cy.request() to communicate with their APIs programmatically. Cache results using cy.session() to avoid repeat visits and improve test performance.

8. Run Independent Tests

It's essential to write tests that are independent of each other and can be run in any order. Avoid coupling multiple tests together, as this can lead to unreliable and unpredictable test results.

To achieve this, use before or beforeEach hooks to set up the initial state for each test. This ensures that tests start with a clean slate and do not depend on the state left by previous tests.

9. Run Small Tests with a Single Assertion

Cypress stands apart from conventional unit testing by executing a sequence of asynchronous lifecycle events that effectively reset the testing environment between each test case. Consequently, employing individual assertions within separate tests can significantly slow down test execution and severely impact performance.

Opting for multiple assertions within a single test is a more efficient approach compared to creating distinct tests. Therefore, feel confident about incorporating multiple assertions within a single test. Each test run is saved into Cypress Cloud App.

10. Use Data Attributes When Selecting Elements

One of the foundational principles of effective E2E testing is selecting elements in a way that's resilient to changes in your application's codebase. To achieve this, prefer using custom data attributes like data-cy or data-testid when identifying elements for testing. These attributes are explicitly designed for testing purposes and are less likely to change due to styling or behavior updates.

11. Independent it() Blocks

When writing test cases in Cypress, it's essential to ensure that each it() block is independent of others. Avoid dependencies between test cases, as this allows for better test isolation. If one test fails, it won't impact the execution of other tests.

This approach ensures that the test suite remains stable and reliable even as it grows in complexity.

12. Use Dynamic Waiting

Avoid static waits, such as cy.wait(timeout), when waiting for page actions like loading or API responses. Static waits can lead to unnecessary delays and brittle tests. Instead, consider using cy.intercept() to wait for specific API responses before proceeding with your test.

javascript

cy.intercept('POST', '**/login').as('login'); cy.visit("/") cy.wait('@login')

Dynamic waits speed up script execution and make your tests more efficient and reliable.

13. Leverage before(), beforeEach(), after(), and afterEach()

To eliminate repetitive code at the beginning or end of each test case, utilize Cypress hooks like before(), beforeEach(), after(), and afterEach(). These hooks allow you to execute common setup and teardown code for multiple test cases.

For example, you can set up a common base URL for all your tests in the before() hook, reducing redundancy and improving maintainability.

14. Adding BaseUrl in the Config File

Hardcoding the base URL in each spec file's before() block can lead to inefficiencies and inconsistencies. Instead, define the base URL in the cypress.json configuration file to ensure that all spec files use the same base URL. This practice streamlines your test setup and makes it more professional.

15. Define Scripts in package.json

To simplify the execution of Cypress commands, define them in the scripts section of your project's package.json file. This allows you to run commands using a user-defined name, enhancing the clarity and ease of running tests.

16. Harness Cypress's Unique Features

Cypress offers several unique features that set it apart from other testing tools:

- Time Travel: Cypress captures snapshots of your application during test execution, allowing you to rewind to any point in your test script. This feature simplifies debugging and error identification.

- Retry-ability: Cypress's automatic retry mechanism ensures that tests proceed as soon as assertions pass, reducing the need for hard-coded waits. This feature is especially useful for testing dynamic web applications.

- Effective Element Selection: Cypress's cy.get() method efficiently locates web elements without explicit waits, making tests faster and more reliable.

- Spies, Stubs, and Clocks: Cypress provides tools to verify and control functions, server responses, and timers, offering the flexibility and control typically associated with unit testing.

17. Run Cypress Tests in Parallel

To expedite test execution and achieve faster feedback, consider running Cypress tests in parallel using cloud infrastructure services like BrowserStack. Parallelization can significantly reduce the time it takes to complete your test suite, allowing for quicker integration and deployment cycles.

Conclusion

By following these Cypress best practices, you can create robust and efficient E2E tests that ensure your web application performs flawlessly. While implementing some of these practices may initially seem challenging, the long-term benefits of improved test stability and faster execution are well worth the effort.

Cypress has revolutionized test automation with its unique features, and when used effectively, it can be a game-changer for your testing efforts.

Happy (automated) testing!

FAQ - Cypress Best Practices

1. What Is Cypress?

Cypress is a powerful JavaScript-based end-to-end testing framework for web applications.

2. How Does Cypress Work?

Cypress runs directly in the browser and executes commands in the same run loop as the application being tested. This allows you to programmatically control and interact with the application.

3. What Are Some Common Cypress Best Practices?

Some common Cypress best practices include: relying on the state instead of waiting for specific elements, using single assertions per test, using descriptive test and command names, organizing test files into logical groups, using custom commands for repetitive actions, using fixtures to add test data, and leveraging Cypress's automatic waiting and retrying.

4. How Can I Define a Custom Command in Cypress?

You can define a custom command in Cypress by adding the command in the "commands.js" file or by defining the command in the "support" folder using the "defineCommand" method. You can then use this custom command in any of your test files.

5. How Can I Add test data in Cypress?

You can add test data in Cypress by using fixtures. Fixtures are JSON files that contain data that can be loaded into your tests using the "fixture" command. This allows you to easily include predefined data in your tests.

6. How Does Cypress Handle Test Cases in a Spec File?

Cypress runs each test case in a spec file independently. This means that each test case starts from a clean state and has no knowledge of the previous test cases. This allows for better isolation and makes tests more reliable.

7. What is end-to-end (e2e) testing in Cypress?

End-to-end (e2e) testing in Cypress refers to testing the entire web application, including the user interface and integration with external systems. It focuses on ensuring that all parts of the application work together correctly and meet the desired requirements.

8. How Can I perform Cypress Test Automation?

You can perform test automation by writing test scripts that can interact with your web application, execute various actions, and verify the expected results. Cypress provides a rich set of commands and assertions to make the automation process easier and more efficient.

10. How Does Cypress Solve the Major Issues in Test Automation?

Cypress solves the major issues in test automation by running directly in the browser and executing commands in the same run loop as the application being tested. This eliminates the need for flaky and unreliable wait times, as Cypress automatically waits for elements and actions to complete before proceeding.

Additionally, Cypress provides powerful assertion capabilities and automatic retries, making it easier to write robust and reliable tests.

Check also our article on the best Cypress alternatives.