Gain insights into Jest, a versatile testing framework. Learn about fundamental and advanced testing techniques, from unit tests to CI/CD integration, for comprehensive JavaScript application testing.

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Jest is a framework for testing applications developed in JavaScript. It has a well-documented and well-maintained range of tools to run tests in parallel. It is simple and works with projects using Babel, TypeScript, Node, React, Angular, Vue, etc. It works well for both client and server testing. 

This course covers Jest in-depth and is agnostic of any specific JavaScript framework. The course begins with the fundamentals of Jest testing, deconstructing the components of a test and covering how to compose basic unit tests and snapshot tests with Jest correctly. Next, it shows the testing of asynchronous code and the code that relies on external dependencies. Lastly, this course illustrates how Jest testing can effectively integrate into the real-world software development cycle through CI/CD pipeline.

It gives you hands-on experience in setting up Jest, types of testing, testing coverage, mocking, and native tooling depth.

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Mastering Jest: A Complete Guide to Testing

## The dimensions of client mocking

There are several high-level elements to keep in mind when mocking inside of our clients. To start, clients run in the browser, and the Jest test environment does not. Since one use for mocking is stubbing out functionality that we cannot or do not want to run in our test environment, we want to keep this in mind.

Additionally, clients typically rely on external services for #key# data hydration: The importing of data into an object. #key#. Whether this is through communication with a server API, a client-side SDK, or something else, this type of external communication more than likely does not work inside our tests. In the best-case scenario, the result is unreliable. Once inside the client, the data might be managed by a global state management system. This system is likely also difficult and unreliable to test.

So, we have two main focal points here: the fact that our clients are built to run in a browser and that they rely on external data in order to function properly. We are going to run through a handful of specific tips that address both of these realities.



# The dimensions of client mocking

There are several high-level elements to keep in mind when mocking inside of our clients. To start, clients run in the browser, and the Jest test environment does not. Since one use for mocking is stubbing out functionality that we cannot or do not want to run in our test environment, we want to keep this in mind.

Learn some quick tips to handle the nuances of client-side code in the Jest test environment.


Client Mock Tips

Learn some quick tips to handle the nuances of client-side code in the Jest test environment.

Introduction

Setting Up Jest

Jest Matchers

Writing Unit Tests

Writing Snapshot Tests

Asynchronous Code

Mocking

Mocking External Libraries

Working with Jest Mocks

Setup & Teardown

Test Coverage & CI/CD Pipelines

Test Coverage in Jest

Conclusion

Bonus: Best Practices

Bonus: Resources for Continued Learning

Appendix

Client Mock Tips

The dimensions of client mocking