Mockito: how to mock method with the result depending on one of its parameters?

Question

Is there a way to pass params to mocked function and use that param value inside. Example (notice name as param):

Mockito.when(clientRepo.registerNewClient(Mockito.any(String.class) as name))
    .thenReturn(
        dslContext
            .insertInto(CLIENT)
            .set(CLIENT.CLIENT_NAME, name)
            .execute());

Is there a way to do that?

Answer 1

You need to use thenAnswer, and get your argument from the InvocationOnMock.

final Repo clientRepo = Mockito.mock(Repo.class);
Mockito.when(clientRepo.registerNewClient(Mockito.any(String.class)))
    .thenAnswer(
        (Answer<Client>)
            invocationOnMock -> new Client(
                invocationOnMock
                    .getArgumentAt(0, String.class)
                    .toUpperCase()
            )
    );
Assertions.assertEquals(
    clientRepo.registerNewClient("fff"), new Client("FFF")
);