Automated Testing in Javascript

    Published on

    December 12, 2022
    Automated Testing in Javascript

    Software testing is a critical activity in software development. Whether you are working on a small software project or a large-scale software system, it is essential to test the quality of your code and identify possible defects. Testing should be considered essential in any significant project you embark on. Still, many people run away from it because it is perceived as complex or too tasking.

    Various testing techniques can be used for testing software applications. When it comes to web applications, there is a lot of debate about which testing method is better – manual or automated tests, unit vs. end-to-end tests, etc. However, regardless of these debates, one thing remains clear: You need to write tests for your JavaScript code and any other code you have written in any language.  

    In this article, we’ll learn about testing in JavaScript, why it is important to include testing in your development workflow, and how to run tests using jest.

    What is Automated Testing?

    Automated testing is a scripted quality assurance procedure that evaluates whether a software application meets its intended results to improve software quality.

    Simply put, automated testing is the process of using a piece of code that is different from the actual source code to control test execution and ensure that our program produces the expected result and if it doesn’t,  it indicates by telling us something isn't right. 

    We call them Automated Testing because a computer can efficiently run through thousands of scenarios or test cases in a matter of seconds without human intervention.

    Why do we have to automate tests?

    Manual Testing our software application is beneficial in the development of our software applications. Automated testing makes it a whole lot easier with more improved benefits. Here are a few reasons you would want to automatically test your code. 

    Automated testing improves the quick detection of bugs at every stage of the software development process, thereby reducing the hours usually used to fix a bug. Automated tests are accurate, and you are less likely to make errors. Being machine based, the risk of failure is slim as machines are less prone to make mistakes.

    Automated Testing is repetitive in nature. Its reusability enables the test to be utilized for testing any aspect of the code, either through significance or different approaches.

    Automated Testing enables High Software Quality and Performance. Automated Test is great at running thousands of test cases simultaneously, which will result in detailed comparative reports in a short time. This means you can run tests on your software against multiple platforms on various devices. Also, you can carry out multiple automated tests quickly, whether lengthy or complex.

    Types of Testing

    Unit Tests

    A unit test involves  testing small pieces/units of code in isolation, such as functions and classes, to ensure they work as expected. A unit test works by giving the function some input and then checking that the function output is correct. Unit testing is the only testing method that encourages writing good code because if your code is poorly designed, writing tests could be complex. So, therefore, the unit test should be reasonably easy to write.

    Integration Tests

    Integration testing ensures that various units/components work together correctly. Integration Testing is being used where unit testing is inadequate. These components could include API and databases. This test is meant to test the interface between the modules and reveal any error that may arise when these components are integrated and need to interact.

    End-to-end tests (E2E)

    Also known as functional testing, E2E tests are used to test software's functionality. Like its name, they test the entire application, its hardware and networking infrastructure, from the end UI to the back-end database systems. However, they are exceptions to the fact that it tests a completed software. This is because there are intricacies and different forms of end-to-end tests.

    How to run a test

    Let’s walk through the process of running a basic unit test with Jest. 

    1. Set up a folder with a name of your choice
    2. Create a file called index.js

    Let’s start by creating a simple function called multiply that would give us the result of multiplying two inputs.

    function multiply(a, b){
          return a * b
        module.exports = multiply;
    1. Next, open your IDE terminal and change directory into the folder where our project lives
    2. Run npm init –y

    This would initialize all the default values and this would gives us a package.json file

    1. Install Jest as a dev dependency in our project  by running npm I --save-dev jest
    2. After that is installed, open your package.json file and change the test property from “test”:”echo /”Error: no test specified/ && exit 1” to “test”:”jest”
    3. Run npm test.
      This would produce a failed result cause we do not have any tests yet
    4. You should have a piece of code you want to test.
    function multiply(a, b){
          return a * b
        module.export = multiply

    Assuming it is in an index.js file, create another file with the same name but in this format: index.test.js

    1. Inside the index.test.js file, import our code from index.js. Specifically the piece of code to be tested
    const multiply = require('./index')
    test('multiplies two numbers correctly',() => {
           multiply(2, 3)
    1. Run npm test

    Awesome. Your first unit test ran successfully

    Test Automation Frameworks

    There are so many testing frameworks, but I will be discussing a few prominent automated testing frameworks for JavaScript. These frameworks help reduce maintenance costs and testing efforts. Count them as an integral part of any successful automated testing process.


    Selenium is an open-source automation testing tool that aids test automation for building modern web apps.


    • It supports multiple programming languages like Java, Javascript, C++, Python, Ruby etc.
    • It supports major browsers such as Chrome, Edge, Firefox and Safari
    • Easy to learn
    • supports a variety of operating systems, including Linux, Mac, and Windows


    • Time-consuming
    • Difficult to set up the test environment
    • There’s a possibility that new features may not work properly
    • Little to no reliable technical support


    Cypress is a trending automation tool used by many people in the market. It is also open source and has a professional package for the Cypress Dashboard, which requires payment to have access. Cypress enables different types of testing, such as Unit testing, Integration Testing and End to End testing. 


    • On a genuine browser, the test can be run.
    • One cool thing about Cypress is that it captures your videos of your test, so you can always make references.
    • It has well-structured documentation, which makes it easy to learn from.


    • It does not enable simultaneous testing on different tabs or browser windows.
    • It restricts the number of superdomains one can visit in one test.


    Playwright is another open-source tool. It has been widely accepted quickly due to its well-structured documentation. It's considered one of the pioneers of headless browser testing, which makes it popular. Playwright supports languages like Javascript/Typescript, Python, Java and C#. Tests are faster with Playwright since it executes the command directly on the browser. It also supports the execution of tests in multiple browsers in parallel.


    • Auto- waiting for elements before performing some actions
    • Automatically makes screenshots and videos of failure 
    • It can be used across multiple browsers


    • Some language bindings are unstable at a time
    • Playwright can’t be extended for Cucumber without third-party plugins or packages.


    WebDrivenIO is equally Open Source and a part of the OpenJS foundation. WebdriverIO, just like its name, uses Webdriver implementation, so it supports all major browsers. Several plugins can be integrated into the framework, giving it more features. 


    • Easy to start
    • Simple and fast to configure
    • There are restrictions to parallel testing


    • Assertions are problematic at the beginning
    • Debugging is possible only through WebDriverIO


    We can't have enough Open Source frameworks and tools. Cucumber is open sourced and has different specifications considered as “flavor”, like cucumber for Javascript, Cucumber for Java, specflow for C#. This is the most popular because of its ability to be integrated into different frameworks. Several frameworks, particularly the major framework, support the Cucumber framework. 


    • Since it is an open source program, cucumber does not need to be licensed
    • Very easy to learn and scalable
    • It's super easy to write and has high reusability, which can be achieved without technical knowledge.


    • Requires user involvement to describe scenarios right
    • Requires steps and scenarios to be maintained


    Jest is an open-source javascript tool framework used to test javascript codes, especially applications developed using React JS. This does not restrict its usage in other languages. It could test Javascript frameworks such as Node, Angular, and Vue applications. It is considered a favorite in the developer community.


    • Easy to set up and configure
    • Captures screenshots to ensure one identifies bugs caused accidentally.
    • Jest has excellent documentation
    • It has a rich API 


    • The screenshot feature is not feasible for larger snapshot files.
    • Less tooling and library support
    • Challenging to use across the boards of different test frameworks
    • Slow when auto-mocking


    Jasmine is an open-source testing framework for Javascript. It has outstanding documentation and a strong community, thereby enabling its popularity. Its value proposition is enormous, thereby making it a favorite in the JavaScript community


    • It is available both for Node and the browser
    • It does not require the DOM
    • It has no external dependencies
    • It is easy to set up
    • Compatible across every framework or library of your choice, making it very flexible


    • It requires a lot of configuration. 
    • An assertion library or mocking framework will be required before using this framework


    Mocha is a flexible Javascript testing framework for testing apps that are developed using Node JS. Mocha is an exciting Open Source tool that guarantees versatility and reliable documentation. Mocha has a great feature that structures the test scripts into test case modules.


    • This framework is open source
    • Great documentation
    • Enables Asynchronous Testing
    • Headless running out of the box


    • It does not allow auto mocking and snapshot testing
    • Requires lots of configuration
    • Mocha snapshot testing is not easy.

    Frameworks to choose from

    It is essential to consider several factors before choosing a framework. With this information in mind, selecting an automated testing framework would be much more convenient for users to make accurate decisions. Below are certain factors to consider when choosing a framework.

    Consider your budget

    To enjoy different features and tools, you should consider investing in frameworks and tools. Factoring how much you have would influence the decision of your framework.

    What features do you need?

    This has a significant role to play in deciding what framework to choose. To make it easier, consider the required features and find out what tool or framework serves your requirement. Some of the features you might want to consider when selecting a framework include: CICD Integration, the ability to manage tests, Support for multiple languages/frameworks, compatibility with different operating systems and technical support

    Comparison table between Cucumber, Selenium, Jest and Mocha


    Testing is a lot helpful in delivering error-free software applications. It also enables easy maintenance and shipping of code. Having written your first test, you should try out more test practice to be accustomed to writing test cases.

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