How to stub get/set of simple types

Question

I am new to Mockito and I was wondering how I could stub a get/set pair.

For example

public interface Order {
     public short getStatus();
     public void setStatus(short status);
}

How can I make them behave properly:

if somewhere in a test I invoke setStatus(4); I would like getStatus() to return 4. How can this be done?

Answer 1

Are you stubbing or mocking?

The difference is whether you are verifying behaviour or providing data for a test. You say:

if somewhere in a test I invoke setStatus(4); I would like getStatus() to return 4.

this implies both at the same time. You either want to verify that setStatus() was called with an argument 4.

verify(mockObject).setStatus(4);

or you want to set your mock object to return 4 when getStatus() is called.

when(mockObject.getStatus()).thenReturn(4);

Mockito has some tutorials which explain how to use it for each situation. I suspect you could do both in your test (but have not checked) but this would be a smell to me, as you should ideally only be checking mocking a single thing in your test, everything else should be stubbed. But, as ever, context is everything and so it may be that you need to stub one part of your object so you can verify the behaviour of another part, in which case it would be fine.

Follow the AAA syntax and arrange your test (ie do the setup and have the when clause) then act (ie call the method on the object under test) then do your asserts (ie have your verify statements)

EDIT

it seems that in the newer versions (1.8+) of mockito it may be possible to do what you want, although it is not recommended. You can use a Spy to create a partial mock of an object. In this case you should be able to create a Spy of your actual object, leave the getStatus() and setStatus() methods un-stubbed (so they are actually called and used) and just stub out the other methods (or just verify they were called presumably). You can read about it in section 13 Spying on real objects on this page.

Answer 2

You can set the behavior of the setStatus method so that it updates the behavior of the getStatus method, as follows:

    Mockito.doAnswer(invocation -> {
        short status = invocation.getArgumentAt(0, Short.class);
        Mockito.when(mockOrder.getStatus()).thenReturn(status);
        return null;
    }).when(mockOrder).setStatus(Mockito.anyShort());