TypeScript is a powerful programming language that enables developers to build large-scale web applications. While TypeScript is not required to use Jest or Supertest, it can be helpful to use TypeScript in conjunction with these testing tools. This article will show you how to set up and use Jest and Supertest with TypeScript.
Before you can start using Jest and Supertest with TypeScript, you need to set up your project. First, install the dependencies:
npm install --save-dev jest @types/jest ts-jest supertest @types/supertest
Next, create a file called jest.config.js
in the root of your project and add the following configuration:
module.exports = {
preset: 'ts-jest',
testEnvironment: 'node',
};
This tells Jest to use the TypeScript compiler and to run tests in a Node.js environment.
Finally, create a file called tests.ts
in the root of your project and add the following code:
import supertest from 'supertest';
const request = supertest('http://localhost:3000');
test('GET /', async () => {
const response = await request.get('/');
expect(response.status).toEqual(200);
});
This code imports the supertest
library and creates a new request
object that will be used to make HTTP requests to the server. The test
function is used to define a test case. In this case, the test case makes a GET
request to /
and checks that the response status code is 200
.
To run the tests, you can use the jest
command:
jest
This will run all tests in your project. You can also run a specific test by passing the test
name as an argument:
jest testName
There are many different ways to write tests with Jest and Supertest. In this section, we'll look at a few common scenarios.
Jest and Supertest can be used to test all HTTP methods: GET
, POST
, PUT
, DELETE
, etc. For example, the following test case tests a POST
request:
test('POST /users', async () => {
const response = await request.post('/users')
.send({
name: 'John',
age: 20,
});
expect(response.status).toEqual(201);
expect(response.body).toEqual({
id: 1,
name: 'John',
age: 20,
});
});
This test case makes a POST
request to /users
with a JSON body. The send
method is used to set the request body. The status
and body
properties of the response are compared to the expected values.
Jest and Supertest can also be used to test middleware. For example, the following test case tests a middleware function that is used to authenticate users:
test('POST /auth', async () => {
const response = await request.post('/auth')
.send({
username: 'test',
password: 'test',
});
expect(response.status).toEqual(200);
expect(response.body).toEqual({
token: 'abcdefg',
});
});
This test case makes a POST
request to /auth
with a JSON body. The send
method is used to set the request body. The status
and body
properties of the response are compared to the expected values.
Jest and Supertest can also be used to test error handling. For example, the following test case tests a middleware function that is used to handle errors:
test('GET /error', async () => {
const response = await request.get('/error');
expect(response.status).toEqual(500);
expect(response.body).toEqual({
error: 'Internal server error',
});
});
This test case makes a GET
request to /error
. The status
and body
properties of the response are compared to the expected values.
Jest and Supertest are powerful tools that can be used to test TypeScript applications. In this article, we've seen how to set up and use Jest and Supertest with TypeScript. We've also seen how to write tests for common scenarios.