Other values may be used in Fit tables, but we need to provide the following extra information about the associated class:
How to convert from a String to an object of the given class. This conversion is defined by the parse() method in the fixture. The method will usually pass control to a static method of the class, such as parse() in Money.
How to create a String from an object of our class. This operation is defined by the toString() of the class.
How to compare two objects of our class for equality. This operation is defined by the equals() of the class.