public void ShouldReturnValueWithDefaultOffset()
        {
            object converted = new ExpanderHeaderWidthConverter().Convert(100.0, null, null, null);

              Assert.IsInstanceOfType(converted, typeof(double));
              Assert.AreEqual<double>(100 + ExpanderHeaderWidthConverter.DefaultOffset, (double)converted);
        }
        public void ShouldTakeDefaultOffsetForWrongParameter()
        {
            object converted = new ExpanderHeaderWidthConverter().Convert(100.0, null, "wrong", null);

              Assert.IsInstanceOfType(converted, typeof(double));
              Assert.AreEqual<double>(100 + ExpanderHeaderWidthConverter.DefaultOffset, (double)converted);
        }
        public void ShouldConvertBackWithCustomOffset()
        {
            object converted = new ExpanderHeaderWidthConverter().ConvertBack(100.0, null, 50, null);

              Assert.IsInstanceOfType(converted, typeof(double));
              Assert.AreEqual<double>(50, (double)converted);
        }