text: jest.dontMock('../r.js');
  var r = require('../r');
  describe('calc r', function() {
   it('r(1,2) = 0.5', function() {
     expect(r(1,2)).toBe(0.5);
   });
   it('r(2,1) = 0.75', function() {
     expect(r(2,1)).toBe(0.75);
   });
  });