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

## Looking deeper into Jest globals
To help with writing and running our tests efficiently, Jest provides several additional globals that we can use. These globals allow us to do things like iterate over test cases and run only the test we are working on.

## Additional functionality of `describe`

+ describe.each(table)(name, fn, timeout)` helps to abstract repetitive testing logic that just needs to be run with multiple data sets. The `table` argument is an array of arrays representing the data to pass to the anonymous function (`fn`) and ultimately for us to use in our individual tests. The name is still the descriptor for the test suite, i.e., function or component name, and we have an optional timeout again.

+ `describe.only(name, fn)` tells Jest to run only this describe block. If a test file has multiple `describe` blocks and we are working on or debugging only one, running all test suites in the file every time is unnecessarily time-consuming. We can use 
`describe.only` to avoid this.

+ `describe.only.each(table)(name, fn)` has the benefits of both the functions above, enabling us to run only the test suite with the dataset we want to pass the function in.
+ `describe.skip(name, fn)` is the opposite of `describe.only`, specifying a test suite that we do not want to run.
+ `describe.skip.each(table)(name, fn)` is the opposite of `describe.only.each`, specifying a test suite and the corresponding dataset that we do not want to run.

### Examples

Examples of each of these are included below. If you run the test file, you’ll see that _only_ the blocks with `describe.only` and `describe.only.each` actually run. This is expected given their functionality. Examples of each are still included to show how they should be used. Feel free to comment out the `.only` tests to see the others in action:



# Looking deeper into Jest globals
To help with writing and running our tests efficiently, Jest provides several additional globals that we can use. These globals allow us to do things like iterate over test cases and run only the test we are working on.

# Additional functionality of `describe`

+ describe.each(table)(name, fn, timeout)` helps to abstract repetitive testing logic that just needs to be run with multiple data sets. The `table` argument is an array of arrays representing the data to pass to the anonymous function (`fn`) and ultimately for us to use in our individual tests. The name is still the descriptor for the test suite, i.e., function or component name, and we have an optional timeout again.

+ `describe.only(name, fn)` tells Jest to run only this describe block. If a test file has multiple `describe` blocks and we are working on or debugging only one, running all test suites in the file every time is unnecessarily time-consuming. We can use 
`describe.only` to avoid this.

+ `describe.only.each(table)(name, fn)` has the benefits of both the functions above, enabling us to run only the test suite with the dataset we want to pass the function in.
+ `describe.skip(name, fn)` is the opposite of `describe.only`, specifying a test suite that we do not want to run.
+ `describe.skip.each(table)(name, fn)` is the opposite of `describe.only.each`, specifying a test suite and the corresponding dataset that we do not want to run.

## Examples

Examples of each of these are included below. If you run the test file, you’ll see that _only_ the blocks with `describe.only` and `describe.only.each` actually run. This is expected given their functionality. Examples of each are still included to show how they should be used. Feel free to comment out the `.only` tests to see the others in action:



Explore the tools that Jest provides to help write and run our tests as efficiently as possible.


Additional Globals

Explore the tools that Jest provides to help write and run our tests as efficiently as possible.

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

Additional Globals

Looking deeper into Jest globals

Additional functionality of `describe`

Examples

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

Additional Globals

Looking deeper into Jest globals

Additional functionality of describe

Examples

Additional functionality of `describe`