Ignoring Irrelevant Mock Objects

The following expectation ignores the mock object fruitbat during the test.

ignoring (fruitbat);

During the test any method of fruitbat can be called any number of times or not called at all.

When an ignored object is invoked during the test it returns a "zero" value that depends on the result type of the invoked method:

Return Type	"Zero" Value
boolean	false
numeric type	zero
String	"" (empty string)
Array	Empty array
Mockable type	A mock that is ignored
Any other type	null

The fact that a method with a mockable return type will return another ignored mock object makes the ignoring expectation very powerful. The returned object will also return "zero" values, and any mockable values it returns will also be ignored, and any mockable values they return will be ignored, and so on. This allows you to focus individual tests on different aspects of an object's functionality, ignoring irrelevant collaborators.

For example, the following statement ignores the Hibernate¹ SessionFactory, and the current Session obtained from the getCurrentSession() method, and the Transaction returned from the beginTransaction() method and the commit() and rollback() methods of the Transaction. So you can specify the behaviour of the object independently of how it coordinates transactions and test the transaction management in other tests.

ignoring (hibernateSessionFactory);