public void Given12InchesAdd2FeetShouldEqal3Feet()
{
var twelveInches = new Quantity(12, LengthUnit.INCH);
var oneFeet = new Quantity(2, LengthUnit.FEET);
var threeFeet = new Quantity(3, LengthUnit.FEET);
Assert.AreEqual(threeFeet, twelveInches.Add(oneFeet));
}
public Quantity Add(Quantity quantity)
{
if (IsUnitTypeDifferentFrom(quantity))
throw new ArgumentException();
var thisAmountFactor = UnitConversionFactor.Get(unit);
var otherAmountFactor = UnitConversionFactor.Get(quantity.unit);
return new Quantity(thisAmountFactor*amount+otherAmountFactor*quantity.amount, LengthUnit.INCH);
}
public bool Equals(Quantity other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
if (IsUnitTypeDifferentFrom(other))
return false;
var thisAmountFactor = UnitConversionFactor.Get(unit);
var otherAmountFactor = UnitConversionFactor.Get(other.unit);
return thisAmountFactor*amount == other.amount*otherAmountFactor;
}
public void ShouldThrowExceptionWhenAddWithDifferentUnits()
{
var twelveInches = new Quantity(12, LengthUnit.INCH);
var twoTBSP = new Quantity(2, VolumeUnit.TBSP);
twelveInches.Add(twoTBSP);
}
private bool IsUnitTypeDifferentFrom(Quantity quantity)
{
return unit.GetType().Name != quantity.unit.GetType().Name;
}