ContainsConstraint
ContainsConstraint tests a whether a string contains a substring
or a collection contains an object. It postpones the decision of
which test to use until the type of the actual argument is known.
This allows testing whether a string is contained in a collection
or as a substring of another string using the same syntax.
Flag the constraint to ignore case and return self.
Flag the constraint to ignore line ending format (\r vs. \n vs. \r\n) and return self.
Flag the constraint to ignore white-space and return self.
Initializes a new instance of the ContainsConstraint class.