builder pattern mock

builder.java

/*
* copied from: http://stackoverflow.com/questions/8501920/how-to-mock-a-builder-with-mockito
*/

import static org.mockito.Mockito.RETURNS_DEFAULTS;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;

public class SelfReturningAnswer implements Answer<Object>{

    public Object answer(InvocationOnMock invocation) throws Throwable {
        Object mock = invocation.getMock();
        if( invocation.getMethod().getReturnType().isInstance( mock )){
            return mock;
        }
        else{
            return RETURNS_DEFAULTS.answer(invocation);
        }
    }
}