# How to Isolate Tests in Jest

A Note on the Series:

> Fast Fridays 🏎 is a series where you will find fast, short and sweet tips/hacks that you may or may not be aware of. I will try to provide these (fairly) regularly on Fridays.

When writing unit tests with [Jest](https://jestjs.io/), I often want to isolate a particular test case. I find this especially true when working within a test suite that has gotten pretty large due to the number of features associated with a particular component. 

Instead of taking the manual approach and commenting out the tests cases I want to ignore for the moment, Jest provides two helper methods `test.only()` and `test.skip()` that makes isolating specific tests a lot simpler.

# test.only()
The `test.only()` method is beneficial if you want to ***target*** 🎯 individual tests within a suite. By default, Jest will run all tests within a suite unless instructed otherwise. When a minimum of one test case uses this method, Jest will only run the test cases that reference the `.only()` method. 

I find myself using `test.only()` quite a bit these days. A common workflow for me is to implement a feature and then pinpoint the individual tests that I want to hone in on. This allows me to reduce the amount of output in the terminal and focus on the main task at hand. 

# test.skip()
The `test.skip()` method is helpful if you want to ***omit*** ⏩ certain tests from a suite. When the `.skip()` method is used, Jest will skip over the relevant test case when running the test suite. I don't find myself using this method as often as `test.only()`, but I still find it to be a beneficial method to have in my back pocket.

![Screen Shot 2021-12-16 at 12.54.32 AM.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1639634104823/IgI_76uwy.png)
<cite>Output when `test.only()` or ` test.skip() ` is used on an individual test. </cite>

> 🚨 Warning: Make sure to remove the `.only()` or `.skip()` methods before committing your code. These methods are only meant to be used for debugging purposes and should not be used in final tests.


# El Fin 👋🏽
I hope this quick tip can be useful to you the next time you have to write tests. For an exhaustive list of global objects and methods associated with the `test` object, take a look at the [official documentation](https://jestjs.io/docs/27.2/api#testname-fn-timeout) .

As always, thank you for reading, and happy coding!

#### Resources
- [Jest Docs - test.skip()](https://jestjs.io/docs/27.2/api#testskipname-fn)
- [Jest Docs - test.only()](https://jestjs.io/docs/27.2/api#testonlyname-fn-timeout)