ComparisonConstraint
Abstract base class for constraints that compare values to
            determine if one is greater than, equal to or less than
            the other.
            
                
Switches the .Within() modifier to interpret its tolerance as
            a percentage that the actual values is allowed to deviate from
            the expected value.
            
Initializes a new instance of the  ComparisonConstraint class.
            
protected abstract bool PerformComparison(ComparisonAdapter comparer, object actual, object expected, Tolerance tolerance)
Protected function overridden by derived class to actually perform the comparison
            
Modifies the constraint to use an  IComparer and returns self
            
Modifies the constraint to use an  IComparer<T> and returns self
            
Modifies the constraint to use a  Comparison<T> and returns self
            
Set the tolerance for use in this comparison