         diff = @choroplethMap.calculateDifference(@oldSnippetModel)
         expect(diff[3].properties[0]).to.eql
           label: 'value property'
+          key: 'valueProperty'
           difference:
             type: 'change'
             previous: 'value'

        diff = @choroplethMap.calculateDifference(@oldSnippetModel)
        expect(diff[3].properties[1]).to.eql
          label: 'color scheme'
          difference: undefined
          info: '(YlGn)'


        diff = @choroplethMap.calculateDifference(@oldSnippetModel)
        expect(diff[3].properties[2]).to.eql
          label: 'quantize steps'
          key: 'quantizeSteps'
          difference: undefined
          info: '(3)'

