Testing NodeJS APIs pt. III: set up Jest + Supertest and tasks

Now that we have a server and an API we can set up our test environment/tasks.

Install depencencies

npm i --save-dev cross-env supertest jest

• Jest: testing framework, with a in-built test runner, assertion library and mocking support(and more)
• Supertest: library for testing Node.js HTTP servers, enabling to programmatically send HTTP requests
• cross-env: library that allows to set environment variables in any OS

Now, let's add a test task in the package.json:

"scripts": {
   "test": "cross-env NODE_ENV=test jest — testTimeout=10000"
}

If you try to run this task you will have this output:

npm run test
> cross-env NODE_ENV=test jest — testTimeout=10000
No tests found, exiting with code 1

So let's create a simple test to check if our test setup is correct. Create a test/ folder and there, a sample.test.js:

describe('Sample Test', () => {
   it(‘should test that true === true’, () => {
      expect(true).toBe(true)
   })
})

Now, run again the task:

npm run test
> cross-env NODE_ENV=test jest — testTimeout=10000
 PASS test/sample.test.js
  Sample Test
   ✓ should test that true === true (3ms)
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 1.055s
Ran all test suites.

Now we are ready to write our real tests in the next part!

The full and updated source from the project is in Github and the exact version from this Medium post is here.