Step 4

Let's explore the test script:

const supertest = require("supertest");
const app = require("../server");

const request = supertest(app);

test("Get 200 for API homepage", async () => {
  const response = await request.get("/");
  expect(response.status).toBe(200);
});

We use supertest to wrap the express app. It allows us to send a request to the API without actually running the server.

const supertest = require("supertest");
const app = require("../server");

const request = supertest(app);

request
  .get("/")
  .then((response) => {
    console.log(response.status); // HTTP status code sent by the server
    console.log(response.body);   // The response body sent by the server
  })
  .catch((err) => console.log(err));

All you need in a test file is the test function which runs a test. The first argument is the test name; the second argument is a function that contains the expectations to test.

test("two plus two is four", () => {
  expect(2 + 2).toBe(4);
});

This test used expect and toBe to test that two values were identical.