Best Practices for Writing Reliable and Maintainable Selenium-Mocha Tests


In today’s competitive landscape, it is crucial for websites to provide a flawless user experience in order to succeed. To meet this requirement, QA engineers can rely on reliable and well-established open-source tools like Selenium. These tools not only help minimize manual testing efforts but also allow for faster execution of comprehensive tests. However, to achieve efficient results from Selenium testing, it is essential to have a solid understanding of the relevant best practices.

Mocha, a powerful JavaScript test framework designed to run on Node.js, provides extensive capabilities. By executing tests synchronously, Mocha ensures flexibility, accuracy, and effective mapping of unanticipated outcomes to the correct test cases.

While several testing tools are available, Selenium stands out as the preferred choice in the industry for its robust automation capabilities. It seamlessly integrates development and testing processes, maintaining the momentum of the software development cycle. With automated tests, various aspects of an application, such as stability and security, can be thoroughly examined without disrupting the workflow.


What is the Selenium Framework?

The Selenium Framework is a widely recognized and extensively employed collection of testing tools that enables the automation of interactions with desktop and mobile web browsers. With the Selenium Framework, testers can automate a range of testing activities, including navigation, form filling, clicking, scrolling, and more.

Among the tools in the Selenium suite, Selenium WebDriver is the most popular and frequently utilized. It serves as a browser automation framework, empowering testers to create automated regression tests for their applications. Selenium WebDriver supports multiple programming languages, such as Java, Python, Ruby, and C#, providing developers with flexibility and versatility in writing test scripts.

What is Mocha?

Mocha is a JavaScript test framework designed to run tests on Node.js. It can be easily installed as a Node package using ‘npm’, allowing you to use alternative assertion libraries in place of Node’s standard ‘assert’ function, such as ChaiJS. Mocha shares similarities with Jasmine, another popular test automation framework that we have mentioned in our research on Front End and Unit Test Automation Trends.

Mocha offers an API that provides a structured way to organize testing code into test suites and test case modules for execution, as well as generating test reports. You can choose to run Mocha either through the command line interface (CLI) or programmatically using the Mocha API.

Mocha provides an API that enables the structuring of testing code into test suites and test case modules for execution and generating test reports. It offers two modes of running tests: through the command line interface (CLI) or programmatically using the Mocha API.


Getting Started with Node.js Unit Testing

Unit testing in Node.js involves testing small code components in isolation within the Node.js application. It plays a crucial role in identifying bugs early on and improving code quality. This section provides a guide on setting up Selenium Node.js unit testing.

Prerequisites for Setting up Selenium Node.js Before getting started, ensure that you have the latest version of Node.js installed on your machine and have set up all the necessary path variables.

Install the Selenium WebDriver to automate your tests. Since the tests will run on your local machine, you’ll need a browser to execute the test cases. Install the latest version of the Chrome Driver package. However, you can install any browser driver package depending on your preferred browser.

Install Mocha

If you plan to use Mocha through the CLI, it should be installed globally in your Node.js environment.

  • npm install -g mocha
  • Install Chai Assertion Module: To install the Chai assertion module, use the following command:
  • npm install –save chai
  • The ‘–save’ option ensures that the module is installed within the project’s scope rather than globally.

Test Suite and Test Case Structure

In Mocha, a test suite is defined using the ‘describe’ keyword, which accepts a callback function. A test suite can contain nested test suites, each of which can have its own child test suites, and so on. On the other hand, a test case is denoted by the ‘it’ function, which also accepts a callback function and contains the testing code.

Mocha supports setup functions for test suites and test cases. The setup function for a test suite is denoted by ‘before’, while the setup function for a test case is specified using ‘beforeEach’. The ‘beforeEach’ function is executed before each test case and serves as a common setup for all cases within the suite.

Similar to setup functions, Mocha also provides teardown functions for test suites and test cases. The teardown function for a test suite is denoted by ‘after’, while the teardown function for a test case is implemented using the ‘afterEach’ function. These functions are executed after the completion of a test suite and after each individual test case, respectively.

Implementing Selenium Testing with Node.js

Step 1: 

  • Project Setup and Dependency Installation
  • Start by creating a new folder for your project and execute the following command in the terminal to generate a package.json file within your project directory.
  • Run the command “npm init” to create a package.json file inside your project folder.
  • Install the Selenium WebDriver using the following command in the terminal.
  • To install the Selenium Webdriver, use the following command: “npm install selenium-webdriver”.
  • Next, install the browser driver.
  • Install Mocha, the testing framework, by running the following command:
  • Install the necessary modules by executing “npm install mocha“.
  • After completing the installations, open the package.json file and edit the “scripts” section

Step 2

  • Setting up a Node.js Test File with Selenium Create a new file in the project folder, for example, sample.js, and add the following script to it.
  • In the project folder, create a new file (e.g., sample.js) and include the following script for your test.

Step 3

  • Executing the Test File

Enter the command “node sample.js” to execute the test.

By following these steps, you can set up your project, install the necessary dependencies, create a test file, and execute the test using Selenium and Node.js.


Best Practices

Node.js is widely adopted for developing robust applications, and by incorporating certain practices when writing scripts, you can greatly enhance their usability.

Here are some practices that can enhance your testing experience:

1. Keep tests concise

Keeping tests concise is an essential practice in Node.js testing. When tests are short and focused, they provide more reliable results. By isolating specific functionalities or components within your application and creating targeted test cases, you can thoroughly evaluate their behavior and functionality.

One of the key benefits of keeping tests concise is that it helps maintain the integrity of your testing outcomes. When a test fails, having shorter tests ensures that the failure does not propagate to other parts of the application or affect subsequent tests. This isolation allows you to pinpoint and address issues more effectively, minimizing the time and effort required for debugging and troubleshooting.

Concise tests also contribute to improved readability and maintainability of your testing codebase. By having smaller test cases, it becomes easier to understand their purpose and intent. This enhances collaboration among team members, as they can quickly grasp the scope and functionality being tested.

2. Embrace BDD (Behavior-Driven Development)

Behavior-Driven Development (BDD) is a software development approach that integrates seamlessly with Node.js and promotes collaboration among project contributors. It provides a common language and framework for stakeholders, developers, and testers to communicate and align their understanding of the application’s behavior and requirements.

By writing test cases in plain English using the Gherkin language, BDD allows for a shared understanding of the expected behavior of the application. This common language promotes better communication and collaboration among team members, regardless of their technical backgrounds.

3. Maintain up-to-date dependencies

Maintaining up-to-date dependencies is crucial for ensuring the stability and reliability of your Node.js applications and testing processes. When dependencies are in harmony with each other, it minimizes compatibility issues, security vulnerabilities, and other potential risks that could affect the overall performance of your tests.

By actively tracking the latest versions of your dependencies and updating them regularly, you can take advantage of bug fixes, performance enhancements, and new features introduced by the package maintainers. This proactive approach not only helps you stay current with the advancements in the Node.js ecosystem but also ensures that your testing environment is optimized for efficiency and accuracy.


4. Utilize Selenium Grid

By executing your tests on Selenium Grid, you gain the ability to test your application on a wide range of operating systems, such as Windows, macOS, and Linux, as well as different browsers, including Chrome, Firefox, Safari, and Internet Explorer. This enables you to replicate real-world user environments and uncover any compatibility issues or inconsistencies that may arise.

The distributed nature of Selenium Grid allows you to run tests in parallel across multiple nodes, significantly reducing the overall test execution time. This scalability is particularly beneficial when dealing with large test suites or when you need to perform extensive cross-browser testing.

5. Implement test reports

Implementing test reports in your testing process can greatly enhance your ability to track the status of your tests and effectively manage failures. Test reports provide valuable insights and information about the outcome of your tests, enabling you to identify issues and take appropriate measures promptly.

When setting up test reports, you establish a mechanism to capture and record the results of each test execution. This includes details such as the test case name, execution time, status (pass/fail), and any associated error messages or stack traces. By having this information readily available, you can quickly assess the overall health of your test suite and pinpoint areas that require attention.

6. Leverage Real Device Cloud

Testing your websites and applications on real devices offers several advantages compared to using emulators or simulators. Emulators and simulators attempt to replicate the behavior of real devices, but they may not accurately represent the wide array of hardware configurations, software versions, and user environments that exist in the real world. This is where real device clouds can greatly enhance your testing capabilities.

LambdaTest is a digital experience testing that provides a comprehensive real-device cloud that allows you to test your websites and apps on a vast range of devices, browsers, and operating systems. Furthermore, you can access thousands of real devices, including smartphones, tablets, and desktop computers, running various operating systems like Android, iOS, Windows, macOS, and more.

This extensive device coverage ensures that you can thoroughly test your application across different platforms, screen sizes, and device capabilities, ensuring a seamless user experience for your target audience.



It is essential to prioritize the planning and design of an effective test strategy before writing Selenium-Mocha automation scripts. By dedicating time to consider the test scenarios and approach carefully, you can enhance the efficiency and reliability of your test automation efforts. Working smartly and giving due importance to test design and strategy is crucial in achieving optimal results.

Leveraging greal device clouds provides substantial benefits for your testing efforts. Testing on real devices ensures a more accurate representation of user environments, enabling you to identify and resolve issues that may be missed in emulators or simulators. With support for various testing frameworks, you can choose the one that best suits your needs and conduct comprehensive automation tests.