text: const rot18 = require('./rot18');
  
  describe('rot18', () => {
      const lower = 'abcdefghijklmnopqrstuvwxyz';
      const upper = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
      const numbers = '0123456789';
      const rotatedLower = 'nopqrstuvwxyzabcdefghijklm';
      const rotatedUpper = 'NOPQRSTUVWXYZABCDEFGHIJKLM';
      const rotatedNumbers = '5678901234';
      it('does not rotate lower characters', () => {
          const actual = rot18(lower);
          const expected = rotatedLower;
          expect(actual).toEqual(expected);
      });
      it('does not rotate upper characters', () => {
          const actual = rot18(upper);
          const expected = rotatedUpper;
          expect(actual).toEqual(expected);
      });
      it('rotates upper + numbers +lower correctly', () => {
          const actual = rot18(upper + numbers + lower);
          const expected = rotatedUpper + rotatedNumbers + rotatedLower;
          expect(actual).toEqual(expected);
      });
      it('rotates numbers correctly', () => {
          const actual = rot18(numbers);
          const expected = rotatedNumbers;
          expect(actual).toEqual(expected);
      });
      it('rotating numbers twice nullifies rotation', () => {
          const actual = rot18(rot18(numbers));
          const expected = numbers;
          expect(actual).toEqual(expected);
      });
  });
  