As part of my efforts to create more concise Unit Tests in Java, Steve McLarnon and I recently added the ability to create a stub and stub one method with only one line.

The implementation relies entirely on Mockito, so my example assumes you were already using Mockito to create the stub.

The Mockito documentation has the following example for stubbing:

LinkedList mockedList = mock(LinkedList.class);
when(mockedList.get(0)).thenReturn("first");

LinkedList mockedList = create(aStub(LinkedList.class).returning("first").from().get(0));

public class MockitoExtensions {
    public static  T create(Object methodCall) {
        when(methodCall).thenReturn(StubBuilder.current.returnValue);
        return (T) StubBuilder.current.mockInstance;
    }

    public static  StubBuilder aStub(Class klass) {
        return new StubBuilder(mock(klass));
    }

    public static class StubBuilder {
        public static StubBuilder current;
        public final T mockInstance;
        private Object returnValue;

        public StubBuilder(T mockInstance) {
            current = this;
            this.mockInstance = mockInstance;
        }

        public T from() {
            return mockInstance;
        }

        public StubBuilder returning(Object returnValue) {
            this.returnValue = returnValue;
            return this;
        }
    }
}

From http://blog.jayfields.com