[FIXED] Cannot mock/spy class java.util.Optional

Issue

I'm trying to implement this JUnit code:

private BinlistsService binlistsService = Mockito.mock(BinlistsService.class);

@Mock
Optional<BinLists> binList = null;

@BeforeEach
    public void beforeEachTest() throws IOException {

        BinLists binLists = new BinLists();
        binLists.setId(1);
        ....

        binList = Optional.of(binLists);
    }

    @Test
    public void testBinCountryCheckFilterImpl() {

        when(binlistsService.findByName(anyString())).thenReturn(binList);

}

But I get this error stack:

org.mockito.exceptions.base.MockitoException: 
Cannot mock/spy class java.util.Optional
Mockito cannot mock/spy because :
 - final class
    at org.data

Do you know how I can fix this issue?

Solution

Remove @Mock on the Optional<BinLists> field.

Optional is a simple class that can be easily created and controlled by you, so you do not need to mock it .Just create an actual instance when you need it which you already do it in beforeEachTest() :

private BinlistsService binlistsService = Mockito.mock(BinlistsService.class);

Optional<BinLists> binList = null;

    @BeforeEach
    public void beforeEachTest() throws IOException {

        BinLists binLists = new BinLists();
        binLists.setId(1);
        ....

        binList = Optional.of(binLists);
    }

    @Test
    public void testBinCountryCheckFilterImpl() {

        when(binlistsService.findByName(anyString())).thenReturn(binList);

}

Answered By - Ken Chan