Testing on the Backend: A Beginner’s Guide

Why Test on the Backend?

Testing on the backend is crucial for several reasons:

• It ensures that your API endpoints are working correctly
• It helps catch bugs and errors before they reach production
• It improves the overall quality of your codebase

Using Node.js for Testing

Node.js has a built-in test runner that makes it easy to write and run tests. To get started, you’ll need to create a new project and install the required dependencies.

Project Setup

Create a new directory for your project and navigate into it in your terminal or command prompt. Run the following command to create a new Node.js project:

npm init

Next, install the required dependencies:

npm install --save-dev jest

Writing Tests with Node.js

Create a new file called index.test.js and add the following code:

const assert = require('assert');

describe('Example Test', () => {
  it('should pass', () => {
    assert.strictEqual(2 + 2, 4);
  });
});

This code defines a simple test that checks whether the sum of 2 and 2 is equal to 4.

Running Tests with Node.js

To run the test, use the following command:

node index.test.js

You should see the test pass.

Using Jest for Testing

Jest is a popular testing framework for JavaScript that provides a lot of features out of the box. To get started with Jest, you’ll need to install it as a dev dependency:

npm install --save-dev jest

Project Setup

Create a new directory for your project and navigate into it in your terminal or command prompt. Run the following command to create a new Node.js project:

npm init

Next, install the required dependencies:

npm install --save-dev jest

Writing Tests with Jest

Create a new file called app.test.js and add the following code:

describe('Example Test', () => {
  it('should pass', () => {
    expect(2 + 2).toBe(4);
  });
});

This code defines a simple test that checks whether the sum of 2 and 2 is equal to 4.

Running Tests with Jest

To run the test, use the following command:

jest

You should see the test pass.

Jest 28: New Features

Jest 28 was released in April 2022 and brought along a lot of new features. One of the most requested features is called sharding. Essentially, sharding lets you split your test suite into different shards to run a fraction of your suite tests. For example, to run a third of your tests, you could use the following command:

jest --shard-id=1 --shard-count=3