Testing a REST API in Node JS with Express using Mocha and Chai 😎

Table Of Contents

• What is Unit testing
• Why using Unit testing?
• Who use Unit testing?
• Conclusion

What is Unit testing ?!

Is a software testing method by which individual units of source code and typically automated tests written and run by software developers to ensure that a section of an application (known as the "unit") meets its design and behaves as intended.

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Why using Unit testing

Testing is one of those things that people either love or hate. Usually testing is something that is hated

• Until you work on a project with good tests and you realize how amazing they are.
  I will talk about the code you need in order to write tests in JavaScript using chai and mocha, as well as show you some pitfalls of testing.

• At the end of the article I will breakdown the importance of testing and some best practices you can adhere to in order to make your tests amazing.

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Who use Unit testing ?!

To get started in this trip, I have simple REST APIs already created (Get, Post, etc.)

• And these are very simple server-side Nodejs with Express APIs GitHub repository link
  in our case we have a route get all tasks which response with a small array of tasks.

• As we mentioned at the beginning of this article we gonna talking about testing and how to test on JavaScript and an the easiest way to that in my opinion is to use both library(chai and mocha)

Chai is an assertion library for NodeJS and browser with three styles [ should, Expect, Assert]

Mocha is a testing framework for JavaScript, each is an incredibly and well-built testing library for JavaScript

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1.In order to start this all we need to do is to install two libraries with

run npm i mocha chai --save--dev

2.Now that is done downloading we come here where we have test script and we can change this by typing in "test": "mocha"

3.So to get started creating first test all need to do is create folder called test and add a new file task.js give it the exact same name as file you want to test in our case we will test

4.Now inside this file all need to do to import routes file (task.js) including all APIs and in order to write test we need to import chai then adding Assertion

'

5.Now we are able to call our RESTful APIs and in order to use mocha describe our test let's call it tasks API, then we define an arrow function so first task to describe Get API let's call it Get-All-Tasks then user It to describe what our API do it should Get all the tasks

6.Here we use chai with chai.request(server) and test our Get API .get("/api/tasks") the we expect using .end((err, response) which will receive error and response so we expect a successful results so response should have status 200 and body should be an array with 3 tasks

7.finally call Done(), and run using npm test and the test run successfully

If you need to request wrong route to show API response we make small changes

Test the GET (by Id) route the same steps but we will add task id and in response we will check for returned properties

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Conclusion

Testing one of the most important skills you can known as a developer, It's something a lot of people don't teach or focus on but if you known testing, It's gonna set you apart from every other developers that doesn't known testing and give you extra leg up when you applying for jobs

Comments

[Ibrahim Kamal]

great article

tslam edak ya handasa

[muhammed Lotfy]

Thank you ❤️

[Mohammed Abdullah]

Great article 👌

[muhammed Lotfy]

Thanks 💜

[Rabby Hossian]

Do I need additional setup if API needs database connection ?

[muhammed Lotfy]

No, I have been used a global object instead of DB @rabbyhossain

[Farhana-Ahmed]

great article