@Test
public void captureArguments() throws Exception {

    User user = new User(mockWebService, USER_ID, PASSWORD);
    user.login(mockLoginInterface);
    verify(mockWebService).login(anyInt(), anyString(), responseArgumentCaptor.capture());
    Response response = responseArgumentCaptor.getValue();
    response.onRequestCompleted(true, null);
    verify(mockLoginInterface).onLoginSuccess();
}