Скачать или смотреть How to Mock the new Audio() Class in Jasmine for JavaScript Testing

Learn how to effectively mock the `new Audio()` class in Jasmine to test audio-related functions in JavaScript. Follow our step-by-step guide for seamless unit testing.
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This video is based on the question https://stackoverflow.com/q/68669750/ asked by the user 'Arash' ( https://stackoverflow.com/u/3773888/ ) and on the answer https://stackoverflow.com/a/68670046/ provided by the user 'Daniel A. White' ( https://stackoverflow.com/u/23528/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Mock the new Audio() Class in Jasmine for JavaScript Testing

When developing web applications, it’s common to add audio functionality to enhance user experience. However, unit testing these audio-related functions can present challenges, especially when trying to mock the Audio class in Jasmine. In this post, we will explore how to effectively mock the new Audio() class for testing purposes in Jasmine, enabling you to carry out seamless and effective unit tests.

The Challenge: Testing Audio Functionality

Imagine you have a method in your JavaScript application that plays a sound when invoked. Here’s a simplified version of that method:

[[See Video to Reveal this Text or Code Snippet]]

You want to write unit tests to ensure that audio.play().then(); is called correctly. The problem arises because directly spying on the Audio constructor using spyOn(global, 'Audio'); does not yield the expected results—this is because global is not the correct context for browsers.

The Solution: Using the Correct Context

To effectively mock the Audio class, you need to use the correct global context. Here’s how to do it step by step:

Step 1: Switch to the Window Object

Instead of attempting to spy on global, you should spy on the Audio object within the window context. This can be achieved using the following code:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Setting Up the Spy

To ensure that your tests run correctly, it’s essential to set up the spy to return a mock implementation of the Audio class. Here’s a simple example of how you might set this up in your test suite:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Verifying Function Behavior

With the above code in place, your test will now be able to successfully verify that audio.play() is called when playSound() is invoked. The use of jasmine.createSpyObj allows you to create a mock object that behaves as expected without needing to manipulate any actual audio files. This approach preserves the ability to test your functionality without side effects, providing a clean and efficient way to perform unit tests.

Conclusion

Mocking audio functionality in your JavaScript code can be daunting, but with the right strategy, it can be accomplished smoothly using Jasmine. By switching from global to window, and implementing a spy on the Audio class, you can effectively test your audio-related methods. This not only enhances your testing capabilities but also ensures that your applications maintain high standards of reliability and user experience.

With these steps in mind, you can confidently approach unit testing of any audio-related functionalities in your JavaScript applications. Happy coding!