What is Unit Testing?
Gabriel Villagran -a267572@alumnos.uaslp.mx-
Before I started to show you how to do this, let me talk about what is this and why is important to implement this tests to our projects.
Unit testing is a very useful technique that will help you to develop an application fully functional, Important: If you see a project without testing, be careful, all the projects must have tests and this one should fail and need to be passed.
Unit tests are developed using a framework or library where we will develop the tests that should fail and/or pass and we will develop the code for this test.
How to develop our unit tests using Jest
Jest is a framework for unit testing in JavaScript, this is a step-by-step guide to develop those tests:
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Create a directory where your project will be contained, for example, Ajolonauta
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Using your terminal go to the directory using cd, for example, cd Ajolonauta, once you are there, use the next command:
npm init.
Note: This command will show you some questions for the creation of the project, you can press enter to accept the default values
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Execute the command npm install –save-dev jest to install the Jest package into the newly created project.
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When we run the command to install Jest packages we are going to have a package.json file that needs to be updated, on script section we should changed to something like this:
Final package.json
**Note: The directory node_modules mustn’t have to be versioned, we have to create a .gitignore file on the root directory with the next line: **
Writing your first test
This is a basic test that can be found on the documentation of jest, you can modify for the purpose that you want it:
1-. Create a directory with the name test (here you will code all your tests)
2-. Create a file “myFirstTest.test.js” and write the next sample code:
Run your test
To run your test is very simple, on your terminal execute: npm run test and this will execute all your tests and will show you if the test was pass or fail.
Once you have run your tests, what you need to do now is to refactor your code and once again you need to be sure that your tests fail and pass
The tests of your project are a very important part of it, with them, you can change your code very easily, you will guarantee that your code will work, we do a better design and you can detect errors on an early stage
