Type Parameters:: T - the type of the argument to be matched, when used with the with(Delegate) method

public interface Delegate<T>

An empty interface to be used with the Expectations.result field or the Invocations#with(Delegate) method, allowing test code to define varying invocation results or argument matching rules, respectively.

When combined with the result field, a test will typically assign it with an anonymous class object implementing this interface and containing a delegate method:


    new Expectations() {{
       mock.doSomething(anyInt, anyString);
       result = new Delegate() {
          String <strong>delegate</strong>(int i, String s) {
             return i > 0 ? s : "";
          }
       };
    }};

    tested.exerciseCodeUnderTest();

The delegate class (either named or anonymous) must contain exactly one non-private instance method to be executed when the mocked method or mocked constructor is invoked; it can contain any number of private or static methods, though. The name of the delegate method can be anything. Its parameters, however, should be the same as the parameters of the corresponding mocked method/constructor, or at least be compatible with them. Optionally, the delegate method can have an extra parameter of type Invocation, provided it appears as the first one. The delegate method is also allowed to have no parameters (without counting the optional Invocation parameter).

When used with the result field, the result of a delegate method execution can be any return value compatible with the recorded method's return type, or a thrown error/exception.

When used with the with(Delegate) method, the delegate method must return a boolean, being true for a successfully matched argument or false otherwise.

See Also:

Interface Delegate<T>