DictionaryContainsValueConstraint
DictionaryContainsValueConstraint is used to test whether a dictionary
            contains an expected object as a value.
            
                
Gets the expected object
            
Construct a DictionaryContainsValueConstraint
            
public DictionaryContainsValueConstraint Using<TCollectionType, TMemberType>(Func<TCollectionType, TMemberType, bool> comparison)
Flag the constraint to use the supplied predicate function