@Autowired
    QuestionService questionService;

@PostMapping("/addanswer")
    public ModelAndView editAnswer( ){
        ModelAndView model=new ModelAndView();
        List<Question> q=questionService.findAll();
        model.addObject("answer",q);
        return model;
    }

@ExtendWith(MockitoExtension.class)
public class addAnswerControllerTest {

    @Mock
    private QuestionService questionService;


    @InjectMocks
    private addAnswerController addAnswerController;

   private List<Question>listQ= Arrays.asList(new Question("test1"),new Question("test2"));


    @BeforeEach
     public void setUp(){
       when(questionService.findAll()).thenReturn(listQ);

    }
    @Test
   public void sss(){
        ModelAndView mv=addAnswerController.editAnswer();
       assertThat(mv.getModel()).extracting("answer").contains(listQ);
    }

}

ModelAndView mv=addAnswerController.editAnswer();

java.lang.NullPointerException
	at com.alekseev.Javatesting.addAnswerControllerTest.sss(addAnswerControllerTest.java:40)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

ModelAndView mv=addAnswerController.editAnswer();

@RunWith(SpringJUnit4ClassRunner.class)
@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
public class addAnswerControllerTest {
    TestRestTemplate restTemplate=new TestRestTemplate();
    @Autowired
    private QuestionRepo questionRepo;


    @Before
    public void before(){
        Question question=new Question();
        question.setText("AAA");
        questionRepo.save(question);
    }
    
    @Test
    public void EditAnswer() {
       ResponseEntity<List<Question>> responseEntity= restTemplate.exchange("http://localhost:8080/fa", HttpMethod.GET, null, new ParameterizedTypeReference<List<Question>>() {
        });
       List<Question> list=responseEntity.getBody();
       assertThat(list.size(),is(1));

    }
}

Hibernate: alter table user_quest drop constraint FKm1qm44n06js0fj5m29ek4kayv
Hibernate: alter table user_quest drop constraint FKb5owhjxbj8u2r10eqtvusyong
Hibernate: alter table usr_answer drop constraint FK9rl12nos651kelu5r20dw9ney
Hibernate: alter table usr_answer drop constraint FKlmsuvddkn5nqdu1r1yoo6a3xy
Hibernate: drop table answer if exists
Hibernate: drop table question if exists
Hibernate: drop table user_quest if exists
Hibernate: drop table usr_answer if exists
Hibernate: drop table usr_test if exists
Hibernate: drop sequence hibernate_sequence if exists

Process finished with exit code -1