The Beginner’s Guide to Unit and Integration Testing in JavaScript

What is a unit test?

Unit testing verifies that the code in the so-called “unit” codebase (a small part that can be isolated) works as it should, and that the fully isolated approach is used when testing the small component of the application according to the expected behavior. Since the term “completely isolated” is used here, it implies that the developer requires the application to be isolated from external sources or dependencies, such as databases, servers, etc. HTTP or file system. Unit tests become faster and more stable because they don’t crash due to integration issues with these external services.

Best practices for creating unit tests

The following are best practices for creating unit tests:

  • Test cases need to run at high speed for developers. Developers need fast and simple tests The development team won’t be able to run the test cases often if they are slow.
  • Simple unit test cases also lead to more accurate test results.
  • Implementation logic should not be repeated in test cases.
  • For deterministic test cases, they should work the same as long as the code doesn’t change and while performing deterministic testing you must use real devices and browsers, not a simulator. simulation and emulator. Without exposure to the actual production environment, the test results will be inaccurate or conclusive.
  • An effective naming convention helps highlight test cases.

Selenium JavaScript Framework for Unit Testing

Unit testing for JavaScript involves writing JavaScript code to test all the functionality of a website or web application module. After adding the code to the HTML as a built-in event handler, it will be executed in the browser. Test suites are created by organizing unit tests.

There are different frameworks available for JavaScript unit testing. Here are some of them:

Node.js: Node.js and a browser-based validation library for Javascript. There are many test runners and unit test frameworks that can be used with this framework, such as Protractor, Karma, Mocha, QUnit, Jasmine, etc.

Jasmine: Using Jasmine, you can easily write JavaScript code tests. It does not require the DOM or any other JavaScript framework and has an easy to understand syntax that makes writing tests simple.

Mocha: The framework works in both the browser and Node.js. Tests are run sequentially in Mocha, providing flexibility and accuracy in reporting while also detecting uncaught exceptions and mapping them to the correct test case.

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Joke: Unit tests are usually not very useful when running on a front end app, so this open source framework is built to work with React and React Native based web apps. Configuring UI unit testing can be time consuming, but Jest makes the process much easier.

Karma: The main goal of Karma is to provide developers with an efficient environment to run tests. Where developers don’t have to set up a lot of configuration, but where they can code and get instant feedback. You can run your code on a headless instance of PhantomJS or in a real browser on a real device like a mobile phone, tablet or desktop.

Cypress: Mocha-based JavaScript framework for performing Cypress E2E testing. JavaScript tests can be run in the browser using Cypress, allowing for convenient and easy asynchronous testing. Unit tests in Cypress are run even without a web server. Therefore, Cypress is ideal for testing JS/TS libraries intended for browser use.

Integration testing – overview

Basically, integration testing is aimed at verifying that the joint implementation of several units of the program that has been previously unit-tested works correctly. It is very difficult to write integration tests in complex software systems due to the multitude of connections that are suitable for some specific functionality.

Integration testing consists of several common components:

Functional development – writing test cases

Once you have developed your functions first, you can start writing test cases. Test cases are sent to a remote branch office for integration testing.

Build your own integrated test environment

A dedicated environment is essential for testing as it can provide proper monitoring, resource management, and logging capabilities. Therefore, any integration testing should start in a clean environment.

Testing, planning and performance

Testing new business features is essential, and testing should be integrated into a continuous integration server and enabled at development milestones, such as pull request merge. In addition, integration tests can be scheduled or executed after the code and tests are complete.

Integration test results report

Thanks to the test results report, the development team will be updated on the progress so that if there is a problem, the development team can act immediately. However, this reporting must be done through the usual developer tool channels like Slack or Jira to make the process seamless.

Integration tests: why should I do them?

Every software module is component tested, but bugs can still be found. And some well-known reasons are:

  • The API contains instructions on how to communicate between different components. Having a great API for your business is important because it makes it easier to develop computer programs. To incorporate easy-to-use layouts, modules often interface with these third-party tools or APIs. But integration testing is valuable to verify that what is received from the API is correct and meets expectations.
  • It is not uncommon for data to change when passed from one module to another; The developer may have designed the module differently from what was actually delivered. Due to such changes, it causes problems in module integration.
  • Manual testing is problematic because each aspect of the system is considered separately. For this reason, developers must use integration testing to ensure that the final product is bug-free.
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What is mock test?

Mocking allows you to create a mocked instance of an external or internal service that can be used as a replacement for the real service, making your tests faster. In cases where you are interacting with the properties of an object rather than its behavior or functionality, mock mode can be used.

What is a stub test?

In case your implementation only interacts with a specific behavior of an object, you can use a partial to emulate that behavior instead of the whole object.

Mocking and tampering in unit tests

If your program uses external dependencies, such as system calls or database access, mocking or exploiting is a good idea. You practice deployment whenever you run tests. Assume that when you use delete/create, you are disallowing the process to function properly, allowing the process to create or delete files and data for which the creation and deletion process is not useful. Furthermore, you will have to go through the process of manually deleting something every time. And again, it’s very expensive to clean. Taunting/taunting can be of great help in this case.

Let’s use an example. Imagine that the test writes a file to a .txt file and then the system under test deletes the file. This indicates that the real problem is not whether the test is independent or not, but the slow system call rate. In that case you can jam the response from the file system call, which will take much less time as it will return immediately.

Mocking in integration testing

As part of integration testing, you evaluate relationships between services. One approach is to start and run all the dependent services for the test environment. However, this is not necessary. You may encounter multiple points of failure due to services that you cannot control, which increases the complexity and time required for testing. You should write some service integration tests with model and header to narrow your scope. Integration testing follows different rules than unit testing. Here, you should only test functionality and implementations over which you have control. You can use pseudo and header for this purpose. First, determine which integration is important. Then decide which external or internal services can be mocked.

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Test: What makes it good?

Launching a successful software product requires thorough testing. If your software doesn’t work properly, the end user won’t buy or use it. Even so, error checking takes time. It’s repetitive, expensive, and error prone. Before releasing software to the public, you need to spend enough time testing each component.

Here are some tips. You can’t automate every test, so it’s important to decide which tests you want to automate first. Automating the following will benefit you the most:

  • Testing often leads to operational failure.
  • The tests require multiple records.
  • A test designed to identify frequently used functions that can lead to high-risk conditions.
  • These tests require a lot of time and effort to run manually.

You should also check in often and early. Run your tests immediately and repeat them as often as needed to capture the full potential of your product.

Last word

Faster time to market of your web app is possible if you run unit tests during the development phase. So a unit testing framework that generates fast unit tests, in addition to providing Selenium support, is crucial. As part of this article, we introduced several frameworks for unit testing. You can use the unit testing frameworks discussed to perform automated browser testing of your web application on cloud-based testing platforms such as LambdaTest. It provides a web browser family of more than 3000 combinations of browsers and operating systems for your test automation needs. In addition, it provides premium features like Cypress testing, Selenium testing, Appium testing and HyperExecute to take your automation testing experience to the next level.

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