old_contents: 
    describe('checkbox tests', function () {
  
      it('Should have MaterialCheckbox globally available', function () {
        expect(MaterialCheckbox).to.be.a('function');
      });
  
      it('Should be upgraded to a MaterialCheckbox successfully', function () {
        var el = document.createElement('div');
        el.innerHTML = '<input type="checkbox" class="wsk-checkbox__input">';
        componentHandler.upgradeElement(el, 'MaterialCheckbox');
        var upgraded = el.getAttribute('data-upgraded');
        expect(upgraded).to.contain('MaterialCheckbox');
      });
    });
  
new_contents: 
    describe('checkbox tests', function () {
  
      it('Should have MaterialCheckbox globally available', function () {
        expect(MaterialCheckbox).to.be.a('function');
      });
  
      it('Should be upgraded to a MaterialCheckbox successfully', function () {
        var el = document.createElement('div');
        el.innerHTML = '<input type="checkbox" class="wsk-checkbox__input">';
        componentHandler.upgradeElement(el, 'MaterialCheckbox');
        expect($(el)).to.have.data('upgraded', ',MaterialCheckbox');
      });
    });
  
subject: Update MaterialCheckbox unit test with chai-jquery