Spring:Mocking

 @Spy
 private ItemMapper itemMapper = Mappers.getMapper(ItemMapper.class);

Or alternativly to enable spring dependency injection via

@SpringBootTest(classes = {ItemMapperImpl.class}).

Beispiele

Mockito.when(compoundDocumentRepository.save(Mockito.any(CompoundDocumentEntity.class)))
        .thenAnswer(invocation ->
                {
                    CompoundDocumentEntity compoundDocumentEntity = invocation.getArgument(0);
                    compoundDocumentEntity.setCreatedAt(Instant.now());
                    compoundDocumentEntity.setUpdatedAt(Instant.now());
                    return compoundDocumentEntity;
                }
        );

Mockito.when(session.getUser()).thenReturn(user);

ReflectionTestUtils.setField(compoundDocument, "dbId", 5L);