Writing unit tests in Node is very easy, we are going to use 2 tools for doing that: Mocha and Chai.
Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun
– https://mochajs.org/
Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.
– https://www.chaijs.com/
First of all, make sure you have installed Node in your computer, you can get it here: https://nodejs.org
In your workspace folder, run the next command to init a node package, and complete the requested parameters.
npm init
Run the following command to install Mocha and Chai as a dev dependency
npm install --save-dev mocha chai
Let’s write a simple function that adds 2 numbers
const add2Numbers = (x, y) => {
return x + y;
};
Let’s write the test for that function
// First we have to require chai
const chai = require("chai");
describe("add2Numbers()", () => {
// Description of the test
it("should add 2 numbers", () => {
const x = 1;
const y = 2;
const sum = x + y;
const sumByFunction = add2Numbers(x, y);
// Our assert function
chai.expect(sumByFunction).to.be.equal(sum);
});
});
Next step is to run our tests, go to package.json, and add the «directories» property if not set already. Inside directories, we add another key named «test» that will have the value of the directory where we are saving our test files. Also, we need to add our test script, that will be just «mocha».
package.json
{
.
.
.
"directories": {
"test": "test"
},
"scripts": {
"test" : "mocha"
}
.
.
.
}
So far, our project structure should look like this.
src
- package-lock.json
- package.json
- tests
- - example.test.js
We do the tests running the next command
npm test
The output should look like this
mocha
add2Numbers()
✓ should add 2 numbers
1 passing (11ms)
So far so good! Now you know how to write tests in Node.
You can find the code here https://github.com/samosunaz/node-tests
OsunazTech 