old_contents: 
  describe("Inverted Index", () => {
    const invertedIndex = new InvertedIndex();
    let books = [];
    let books1 = [];
  
    beforeEach(() => {
      books = [
        {
          "title": "Alice in Wonderland",
          "text": "Alice falls into a rabbit hole and enters a world full of imagination."
        },
  
        {
          "title": "The Lord of the Rings: The Fellowship of the Ring.",
          "text": "An unusual alliance of man, elf, dwarf, wizard and hobbit seek to destroy a powerful ring."
        },
  
        {
          "title": "I love to sing",
          "text": "I love to sing and dance and everytime I do that I feel happy and loved"
        }
      ];
  
      books1 = [
        {
          "title": "Harry Porter and the prisoner of azkaban",
          "text": "Harry porter tries to eat rice and beans in the prisoner of azkaban."
        },
  
        {
          "title": "The wizard of OZ.",
          "text": "A wizard comes to town with a powerful ring and falls into a rabbit hole."
        }
      ];
    })
  
    afterEach(() => {
      invertedIndex.indexes = {};
    })
    
    it("should return the instance of the class", () => {
      let indexInstance = invertedIndex;
      expect(indexInstance).toEqual(jasmine.any(Object));
      expect(Object.keys(invertedIndex.indexes).length).toBe(0);
    });
  });
new_contents: 
  describe("Inverted Index", () => {
    const invertedIndex = new InvertedIndex();
    let books = [];
    let books1 = [];
  
    beforeEach(() => {
      books = [
        {
          "title": "Alice in Wonderland",
          "text": "Alice falls into a rabbit hole and enters a world full of imagination."
        },
  
        {
          "title": "The Lord of the Rings: The Fellowship of the Ring.",
          "text": "An unusual alliance of man, elf, dwarf, wizard and hobbit seek to destroy a powerful ring."
        },
  
        {
          "title": "I love to sing",
          "text": "I love to sing and dance and everytime I do that I feel happy and loved"
        }
      ];
  
      books1 = [
        {
          "title": "Harry Porter and the prisoner of azkaban",
          "text": "Harry porter tries to eat rice and beans in the prisoner of azkaban."
        },
  
        {
          "title": "The wizard of OZ.",
          "text": "A wizard comes to town with a powerful ring and falls into a rabbit hole."
        }
      ];
    })
  
    afterEach(() => {
      invertedIndex.indexes = {};
    })
    
    it("should return the instance of the class", () => {
      let indexInstance = invertedIndex;
      expect(indexInstance).toEqual(jasmine.any(Object));
      expect(Object.keys(invertedIndex.indexes).length).toBe(0);
    });
  
    describe("Read book data", () => {
      it("should read the content of a json file and return false if the file is empty", () => {
        let book = [];
        let readBook = invertedIndex.readBookData(book);
        expect(readBook).toBe(false);
      });
      it("should read the content of a json file and return true if the file is not empty", () => {
        let book = [];
        let readBook2 = invertedIndex.readBookData(books);
        expect(readBook2).toBe(true);
      });
    });
  });
subject: add another test suite to the spec files