public void ToString_WhenCalledAndIsNull_CorrectStringIsSet()
        {
            //Arrange
            double?newValue       = null;
            var    constantObject = new ConstantObject(newValue);

            //Act
            var result = constantObject.ToString();

            //Assert
            Assert.AreEqual(result, "constant");
        }
        public void ToString_WhenCalledAndHasValue_CorrectStringIsSet()
        {
            //Arrange
            const double newValue       = 12;
            var          constantObject = new ConstantObject(newValue);

            //Act
            var result = constantObject.ToString();

            //Assert
            Assert.AreEqual(result, newValue.ToString(CultureInfo.InvariantCulture));
        }