Getting org.mockito.exceptions.misusing.UnfinishedStubbingException: - spring-boot

Question

//Test code
class Topic_Service_test
{
#Mock
private Topic_Repository topic_repository;
#InjectMocks
private Topic_Service topic_service = Mockito.spy(new Topic_Service());
#Test
void get_topic_test()
{
Topic_Table topic = new Topic_Table(2,"java");
Mockito.when(topic_repository.findById(Mockito.anyInt()))
.thenReturn(Optional.of(topic));
Mockito.doReturn(topic).when(topic_service.get_topic(2));//.thenReturn(topic);
Assertions.assertEquals(topic,topic_service.get_topic(2));
}
}
class Topic_Service
{
#Autowired
private Topic_Repository topic_repository;
public Topic_Table get_topic(int id)
{
System.out.println("get topic exec");
return topic_repository.findById(id).orElse(new Topic_Table());
}
}
According to me, topic_service.get_topic(2); in Topic_Service_test class should return the object according to Mockito.doReturn(topic).when(topic_service.get_topic(2)); but actually
it is showing some error, which I am not getting it.
ERROR SHOWING:-
org.mockito.exceptions.misusing.UnfinishedStubbingException:
Unfinished stubbing detected here:
-> at
io.practice.practice_course_api.
Topic_Service_test.get_topic_test(Topic_Service_test.java:53)
E.g. thenReturn() may be missing.
Examples of correct stubbing:
when(mock.isOk()).thenReturn(true);
when(mock.isOk()).thenThrow(exception);
doThrow(exception).when(mock).someVoidMethod();
Hints:
1. missing thenReturn()
2. you are trying to stub a final method, which is not supported
3: you are stubbing the behaviour of another mock inside before 'thenReturn' instruction if
completed

Answer 1

You're using the wrong syntax. It should be:
Mockito.doReturn(topic).when(topic_service).get_topic(2);
That is the syntax you want to use on spies to avoid side-effects (for example: if the method invocation would throw an exception).
#Mock
private Topic_Repository topic_repository;
#InjectMocks
private Topic_Service topic_service = Mockito.spy(new Topic_Service());
Also instead of using it like this, the cleaner way would be to use constructor injection. Consider adding a constructor that has a parameter Topic_Repository and then manually create the spy in your test.