text: describe('sum(a, b)', function () {
    beforeEach(function () {
      this.sum = require('./sum');
    });
    it('is a function', function () {
      expect(this.sum).toBeFunction();
    });
    it('returns a number', function () {
      expect(this.sum(1, 2)).toBeNumber();
    });
    it('add numbers correctly', function () {
      expect(this.sum(1, 2)).toEqual(3);
    });
  });
  