The purpose of writing this article is to clarify that when a newbie learns javascript he goes through many concepts. But he doesn't know how to test code or doesn't have any idea about code testing. Today, I will make you understand how you can start learning javascript as well as writing test code also. So that, from the start phase you are confident about your code.
Today's Topics
- create package.json
- intalling jest via npm
- configuration for running test
- write function & test it.
Don't be panic, this article is very practical.
Step 1 : Create package.json
What is package.json ?
Metadata that is specific to the project. It contains a collection of any given project's dependencies. A web application is used to identify the project and acts as a baseline for users and contributors to get information about the project
To create a package.json
you must have to install nodejs
on your machine that's all. If you don't have nodejs
installed go to this website and install it. Then open an empty folder in vs code, open terminal type npm init -y. After executing this command you can see a file is created named package.json
. 😀 Dig more into understanding package.json
click here
Step 2 : Install jest via npm
This is the simpliest way through this step. go go the existing terminal and type npm install --save-dev jest
.
Step 3 : Configuration for running test
- update your
package.json
's scripts section like this,
"scripts": {
"test":"npx jest --watchAll"
},
"jest": {
"testEnvironment": "node"
},
That's all for now.
Step 4 : writing function & test it
- Make a file like
script.js
- Also make a file
script.test.js
For example,
scripts.js
function sum(a, b)
{
return (a + b);
}
module.exports = sum;
script.test.js
const sum = require('../script')
test('Sum of (1,1) = 2', () =>
{
expect(sum(1, 1)).toBe(2);
})
test('Sum of (2,3) = 5', () =>
{
expect(sum(2, 3)).toBe(5);
})
test('Sum of (3,7) = 10', () =>
{
expect(sum(3, 7)).toBe(10);
})
After writing your function & tests code. Go to terminal
and run npm run test
. You can watch something like this ,
Cool 😎 huh !
Yes, now you got the point that I want to share with you.
From today try to build up writing tests for your code & understand your code better. 💖
Signing off.
Sefat
Top comments (1)
test command should be this
"test":"npx jest --watchAll"