public void DealsWithImproperInputs()
 {
     Assert.Equal(0, WordToNumberConverter.Convert(null));
     Assert.Equal(0, WordToNumberConverter.Convert(""));
 }
 public void ConvertsZeroes()
 {
     Assert.Equal("zero", NumberToWordConverter.Convert(0));
     Assert.Equal(0, WordToNumberConverter.Convert("zero"));
 }