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.

…. To come 

… to come 

Mastering Jest: A Complete Guide to Testing

It's a dependency of the code we are testing.

We need to be able to test that one of its functions was called.

Which option is _not_ a reason to mock a module?


Which option is not a reason to mock a module?

**(True or False)** We cannot mock `new Date()` because it is tied to the current date and time.

(True or False) We cannot mock <code>new Date()</code> because it is tied to the current date and time.

**(Select all that apply.)** Which options represent strategies for mocking?


(Select all that apply.) Which options represent strategies for mocking?

The practice of stubbing out a unit of code, such as a function or object, that the code we are testing depends on

The practice of setting up a server containing only mocked data that can be used for testing purposes

The practice of creating a mockup of the expected user interface

The practice of making fun of other engineers' tests

```
jest.spyOn(axios, () => {
   return {
      post: () => return undefined;
   };
})
```

```
jest.mock('axios', () => {
   return {
      post: () => return undefined;
   };
})
```

Mocking a function allows us to use a special set of matchers. Which option is _not_ one of these matchers?


Mocking a function allows us to use a special set of matchers. Which option is not one of these matchers?

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

Quiz on Mocking