describe('Utils', () => {
  let funcs = [];
  let arr;
  const { compose } = require('./../utils.js');

  beforeEach(() => {
    arr = '1,2,3';
    const join = (args) => {
      const joined = (arr) => arr.join(args);
      return joined;
    };
    const concat = (arr2) => {
      const concatFn = (arr) => arr.concat(arr2);
      return concatFn;
    };
    funcs[0] = join;
    funcs[1] = concat;
  });

  describe('compose should', () => {
    it('return a new array', () => {
      // Arrange & Act
      const newComposition = compose(...funcs);

      // Assert
      expect(funcs).not.toEqual(newComposition);
    });

    it('return a new array with the composed elements', () => {
      // Arrange & Act
      const newCmp = compose(...funcs)(arr);
      // Assert
      expect(newCmp).not.toEqual(arr);
    });

    it('when executed should return a function', () => {
      // Arrange & Act
      const composeFn = compose(...funcs);

      // Assert
      expect(composeFn).toBeInstanceOf(Function);
    });
  });
});