Mocking Object that returns Java 8 Optional Object with Mockito returns Empty Optional

Question

I'm attempting to mock an object that returns a Java Optional object with Mockito:

SomeObject someObject = new SomeObject();
Mockito.when(someSpringJpaRepository.findById(Mockito.any(UUID.class))).thenReturn(Optional.of(someObject));

When someSpringJpaRepository.findById(UUID) is called, it returns Optional.empty.

I'm expecting the method findById() to return someObject.
Any reason why it's returning Optional.empty instead?

Here is the method:

public UUID saveOrder(OrderDTO orderDto) {

        Order order = new Order();
        if (orderDto.getId() != null) {
            Optional<Order> result = orderRepository.findById(orderDto.getId());
            if (result != null && result.isPresent()) {
                order = result.get(); // existing record

            } else {
                order.setId(UUID.randomUUID());
            }
        } else {
            // new record
            order.setId(UUID.randomUUID());
        }

        return order.getId();
    }

And here is the Junit:

@Test
    public void saveOrderTest(){

        @Autowired
        private OrderApiService orderApiService;
        @Mock
        private OrderRepository orderRepository;

        OrderDTO orderDto = new OrderDTO();
        UUID orderID = UUID.randomUUID();
        Order order = new Order();
        order.setId(orderID);

        orderDto.setId(orderID);
        Mockito.when(orderRepository.findById(Mockito.any(UUID.class))).thenReturn(Optional.of(order));
        assertNotNull(orderApiService.saveOrder(orderDto));
    }

Do share the signature of `findById` in the question. If the return type is `Optional` for that method, then your mocking is correct but the expectation is incorrect. If the return type is `T` for the method, then your mocking is incorrect and you might want to change it to `.thenReturn(someObject)`. — Naman, Feb 26 '19 at 16:10
`findById` is the Spring CrudRepository method. I did not override the behavior of this method in the implementation `someSpringJpaRepository` You can find the documentation here: https://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/repository/CrudRepository.html#findById-ID- — Amy Bachir, Feb 26 '19 at 16:15
`findById()` returns `Optional`. You suggested that my expectation is, therefore, incorrect. What should be my expectation in this case? Thanks! — Amy Bachir, Feb 26 '19 at 16:38
If the method returns an `Optional`, the expectation should be that it can return `Optional` in that case. Though if the result is `Optional.empty`, it would still be suspicious to me. — Naman, Feb 26 '19 at 17:36
Yea, it's definitely sketchy! I'm not new to Junit and Mockito so I don't think I have any problems in the code, although I could have made a careless mistake somewhere in the code due to looking at it for a long time. Any suggestions for debugging it? — Amy Bachir, Feb 26 '19 at 17:53
Can you show more code? In example how do you call this repository method and how do you set your mock? — ByeBye, Feb 26 '19 at 20:34

score 4 · Accepted Answer · answered Feb 27 '19 at 17:50

4

Your @Mock in class is doing nothing. You created a separate instance of orderRepository which is not injected into your service class. To inject your mock into context use @MockBean

Difference between @Mock and @MockBean here

answered Feb 27 '19 at 17:50

ByeBye

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score 1 · Answer 2 · answered Feb 26 '19 at 16:19

1

you can try to use spy method

Repository spyRepo = Mockito.spy(someSpringJpaRepository);
Mockito.doReturn(Optional.of(someObject)).when(spyRepo).findById(Mockito.any(UUID.class));

answered Feb 26 '19 at 16:19

swolf

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6

Thanks for the suggestion!, However, switching from mock to spy yielded with the same result, an empty Optional object! – Amy Bachir Feb 26 '19 at 16:39

Mocking Object that returns Java 8 Optional Object with Mockito returns Empty Optional

2 Answers2