Mockito thenReturn 总是 null ，Spring-Boot + Junit5 + Mockito

Question

我正在尝试实现 Mockito 来测试特定方法，但 .thenReturn(...) 似乎总是返回 null 对象，而不是我想要的：

我正在使用 mockito 2.22.0 和 Junit-5 以及 spring-boot 2.0.4.RELEASE

用户结果User=userService.save(userDto); 上面的行总是返回空指针异常。不知道为什么 resultUser 总是返回 null，

我的测试课

 @SpringBootTest
    public class UserServiceTests {
    
    @InjectMocks
    private UserService userService =new UserServiceImpl();
    
    @Mock
    private UserRepository userRepository;
    
    @Mock
    BCryptPasswordEncoder passwordEncoder;
    
    @BeforeEach
    void setUp() throws Exception{
        MockitoAnnotations.initMocks(this);
        
    }
    
    @DisplayName("Test saveRegistrationTest method making call to Repository")
    @Test
    public void saveRegistrationTest() {
        
        User user =new User();
        user.setFirstName("TestFN");
        user.setLastName("TestLN");
        user.setEmail("test@test.com");
        user.setPassword("7asdf7asdfi");
        
        User testUser =new User();
        testUser.setFirstName("TestFN");
        
        UserRegistrationDto userDto = new UserRegistrationDto();
        userDto.setFirstName("TestFN");
        
        when(userRepository.save(testUser )).thenReturn(user);
        
        **User resultUser=userService.save(userDto);**
        
        String firstName=(userService.save(userDto)).getFirstName();
        String lastName=(userService.save(userDto)).getLastName();
        String resultEmailFromRepo=(userService.save(userDto)).getEmail();
        String password=(userService.save(userDto)).getPassword();
        
        assertNotNull(user);
        assertEquals("TestLN", firstName);
        assertEquals("TestLN", lastName);
        assertEquals("test@test.com", resultEmailFromRepo);
        assertNotNull(password);
        assertEquals("7asdf7asdfi", password);
    }

用户实体

 @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String firstName;
    private String lastName;
    private String email;
    private String password;
    
    @OneToMany(cascade = CascadeType.ALL)
    private List<Todo> todoList = new ArrayList<>();

    @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinTable(
            name = "users_roles",
            joinColumns = @JoinColumn(
                    name = "user_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(
                    name = "role_id", referencedColumnName = "id"))
    private Collection<Role> roles;

用户DTO

public class UserRegistrationDto {

    @NotEmpty
    private String firstName;

    @NotEmpty
    private String lastName;

    @NotEmpty
    private String password;

    @NotEmpty
    private String confirmPassword;

    @Email
    @NotEmpty
    private String email;

    @Email
    @NotEmpty
    private String confirmEmail;

    @AssertTrue
    private Boolean terms;

Userserviceimpl 类

   public User save(UserRegistrationDto registration){
        User user = new User();
        user.setFirstName(registration.getFirstName());
        user.setLastName(registration.getLastName());
        user.setEmail(registration.getEmail());
        user.setPassword(passwordEncoder.encode(registration.getPassword()));
        user.setRoles(Arrays.asList(new Role("TEST_USER")));
        user.setTodoList(null);
        return userRepository.save(user);
    }

Answer 1

不要

@InjectMocks
private UserService userService = new UserServiceImpl();

这个“对象”永远不会被spring管理！

---

最佳

@SpringBootTest
class UserServiceTest {
  @Autowired
  private UserService testee;

  @MockBean
  private UserRepository userRepoMock; // done!
  // ... many test methods, like: when(userRepoMock.xxx).thenYYY
  // testee.someMethod()
  // verify(userRepoMock...)
  // ...
}

服务的样子：

@Service // or some other "spring managed bean"
public class UserService {
  @Autowired
  private UserRepository userRepository;
 ...
}

---

正如约翰内斯所说：

@BeforeEach

在此设置中不需要（但无害？？！）。

---

核心问题

当我们使用具体对象实例作为 mockito 的“参数匹配器”时：

when(userRepository.save(someObject)).thenReturn(someMock);

，我们应该确保，当（在测试期间）：

userRepository(someOtherObject)

..被调用，

someObject.equals(someOtherObject)

...是true!("平等匹配器")

否则 mockito 可以/不会匹配该调用。

我们可以通过实现（自定义）equals（和hashCode）方法来解决：

// e.g. with lombok:
@EqualsAndHashCode(onlyExplicitlyIncluded = true)
// ...
class UserRegistrationDto {
  @EqualsAndHashCode.Include
  String name;
}

EqualsAndHashCode(推荐，但要做好！(lombok小字，或手动！))

---

或者通过使用“更广泛的参数匹配器”，例如：

when(userRepository.save(any(UserRegistrationDto.class)).thenReturn(myMockResponse);

..甚至：

when(userRepository.save(any(/*java.lang.Object*/))...

ArgumentMatchers javadoc