text: var expect = require('chai').expect;
  var Calculator = require('../code/calculator');
  var withExponents = require('../code/withExponents');
  
  describe( "withExponents", function(){
      var calculator;
      beforeEach( function(){
          calculator = new Calculator();
          withExponents.call( calculator );
      });
      it( "returns 2^3", function(){
          expect( calculator.pow( 2, 3 ) ).to.equal( 8 );
      });
      it( "multiplies 2^3 and 2^4", function(){
          expect( calculator.multiplyExp( [ 2, 3 ], [ 2, 4 ] ) ).to.equal( 128 );
      });
      it( "divides 2^3 by 2^5", function(){
          expect( calculator.divideExp( [ 2, 3 ], [ 2, 5 ] ) ).to.equal( 0.25 );
      }); 
  });