The Genre Data Service

This lesson is part of a series on creating a REST API for the Chinook database.

Related Links:

• Controllers and Services
• Separating Controllers from Services

Here is the code for genre.data.service.test.js file:

const {getAllGenres, getGenreById, insertGenre, updateGenre, deleteGenre} = require("../src/genres/genre.data.service");
const Genre = require("../src/genres/genre.model");

describe("Genre Data Service", ()=>{
  
  describe("getAllGenres()", () => {
    
    it('should return at least 25 genres', async () => {
      const genres = await getAllGenres();
      expect(genres.length).toBeGreaterThan(24);         
    });

    it('should return an array of Genre objects', async () => {
      const genres = await getAllGenres();
      expect(genres[0].constructor.name).toBe("Genre");

    });

  }) // end of getAllGenres()

  /*
  describe("getGenreById()", () => {

    it("should get the proper Genre when a valid param is passed", async () => {
      const genre = await getGenreById(1);
      //console.log("genre", genre);
      expect(genre.name).toBe("Rock");
    })

    it("should return null if there is no genre with the matching id", async () => {
      const genre = await getGenreById(1111111111111);
      expect(genre).toBe(null);
    })

  }) // end of getGenreById()

  describe("insertGenre()", () => {

    it("The returned id should be greater than 0", async () => {
      const genreId = await insertGenre(new Genre({name:"Some new genre"}));
      expect(genreId).toBeGreaterThan(0)
    })

    it("should throw error if the parameter is not a Genre model object", async () => {
      // we expect the error message to include 'Invalid parameter'
      await expect(insertGenre("BLAH")).rejects.toThrow(/Invalid parameter/);
    })
      
    it("should throw error if the Genre parameter is not valid", async () => {
      // we expect the error message to include 'Invalid Genre'
      await expect(insertGenre(new Genre({name:""}))).rejects.toThrow(/Invalid Genre/);
    })

  }) // end of insertGenre()

  describe("updateGenre()", () => {

    it("should return true on successful update", async () => {
      const result = await updateGenre(new Genre({id:2, name:"JAZZ"}));
      expect(result).toBe(true)
    })

    it("should return false if there is no matching id", async () => {
      const result = await updateGenre(new Genre({id:1111111111, name:"Rock-n-Roll"}));
      expect(result).toBe(false)
    })

    it("should throw error if the parameter is not a Genre model object", async () => {
      // we expect the error message to include 'Invalid parameter'
      await expect(updateGenre("BLAH")).rejects.toThrow(/Invalid parameter/);
    })
      
    it("should throw error if the Genre parameter is not valid", async () => {
      // we expect the error message to include 'Invalid Genre'
      await expect(updateGenre(new Genre({name:""}))).rejects.toThrow(/Invalid Genre/);
    })

  }) // end of updateGenre()

  describe("deleteGenre()", () => {
                
    it("should return true on successful delete", async () => {
      const newGenreId = await insertGenre(new Genre({name:"some new genre"}));
      const result = await deleteGenre(newGenreId);
      expect(result).toBe(true)
    })
    
    it("should return false if there is no matching id", async () => {
      const result = await deleteGenre(11111111);
      expect(result).toBe(false)
    })
    
    it("should throw error if the delete violates a FK constraint", async () => {
      await expect(deleteGenre(1)).rejects.toThrow(/FOREIGN KEY/);
    })
    
  }) // end of deleteGenre()
  */


}) // end of Genre Data Service tests