example.js

const request = require("supertest");
const { Genre } = require("../../models/genre");
const { User } = require("../../models/user");
const mongoose = require("mongoose");

let server;

describe("/api/genres", () => {
  beforeEach(() => {
    server = require("../../index");
  });

  afterEach(async () => {
    await server.close();
    await Genre.remove({});
  });

  describe("GET /", () => {
    it("should return all genres", async () => {
      await Genre.collection.insertMany([
        { name: "genre1" },
        { name: "genre2" }
      ]);

      const response = await request(server).get("/api/genres");
      expect(response.status).toBe(200);
      expect(response.body.length).toBe(2);
      expect(response.body.some(g => g.name === "genre1")).toBeTruthy();
      expect(response.body.some(g => g.name === "genre2")).toBeTruthy();
    });
  });

  describe("GET /:id", () => {
    it("Should return a genre if valid id is passed", async () => {
      const genre = new Genre({ name: "genre 1" });
      await genre.save();

      const res = await request(server).get("/api/genres/" + genre._id);
      expect(res.status).toBe(200);
      expect(res.body).toHaveProperty("_id", genre._id.toString());
    });

    it("Should return 404 if invalid id is passed", async () => {
      const res = await request(server).get("/api/genres/1");
      expect(res.status).toBe(404);
    });
  });

  describe("POST /", () => {
    // We define the happy path, and then in each test, we change on parameter
    // that clearly aligns with the name of the test

    let token;
    let name;

    const exec = async () => {
      return await request(server)
        .post("/api/genres")
        .set("x-auth-token", token)
        .send({
          name
        });
    };

    beforeEach(() => {
      token = new User().generateAuthToken();
      name = "genre1";
    });

    it("should return a 401 if client is not logged in", async () => {
      token = "";

      const response = await exec();

      expect(response.status).toBe(401);
    });

    it("should return a 400 if genre is less than 5 characters", async () => {
      name = "1234";

      const response = await exec();

      expect(response.status).toBe(400);
    });

    it("should return a 400 if genre is more than 50 characters", async () => {
      name = new Array(52).join("a");

      const response = await exec();

      expect(response.status).toBe(400);
    });

    it("should save the genre if it is valid", async () => {
      await exec();

      const genre = await Genre.find({ name: "genre1" });

      expect(genre).not.toBeNull();
    });

    it("should return the genre if it is valid", async () => {
      const response = await exec();

      expect(response.body).toHaveProperty("_id");

      expect(response.body).toHaveProperty("name", "genre1");
    });
  });
});