无法用java类实例化名为exception的@InjectMocks字段

Question

我有一个带有用户定义构造函数的类。

public class Employee   
{
    @Inject
    private MyBean myBean;
    private String abcd;    
    protected Employee(Parameter1 param1, Parameter2 param2)
    { //some operations on method params
    //some operation on mybean
      this.abcd = "some value";
    }
    protected String getAbcd()
    {
        return nrOfAccesses;
    }
    protected void setAbcd(String abcd)
    {
        this.abcd = abcd;
    }
}

测试类别

@RunWith(MockitoJUnitRunner.class)
public class TestEmployee
{

    @Mock
    private MyBean myBean;
    private Parameter1 param1;
    private Parameter2 param2;
    @InjectMocks
    private Employee employee;

    @Before
    public void prepare()
        throws Exception
    {
        //some intialization
        param1 = some value;
        param2 = some value;            
        when(myBean.get(eq("ID"))).thenReturn("1075");
    }
    @Test
    public void testEmployeeID()
    {
        employee = new Employee(param1, param2);
        assertThat(employee.getAbcd(), is("XYZC"));        
    }

作为，我得到了例外

org.mockito.exceptions.base.MockitoException: 
Cannot instantiate @InjectMocks field named 'employee' of type 'class com.xyz.Employee'.
You haven't provided the instance at field declaration so I tried to construct the instance.
However the constructor or the initialization block threw an exception : null
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl$1.withBefores(JUnit45AndHigherRunnerImpl.java:27)
    at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:254)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
    at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.NullPointerException

Answer 1

如果执行employee = new Employee(param1, param2);，则不妨跳过@InjectMocks。

它应该做以下事情：

@InjectMocks
ClassUnderTest cut;
@Mock
Dependency1 dep1;
@Mock
Dependency2 dep2;
@Before
public void setup() {
  initMocks(this);
}

省略@InjectMocks，使用以下代码可以实现相同的行为：

ClassUnderTest cut;
@Mock
Dependency1 dep1;
@Mock
Dependency2 dep2;
@Before
public void setup() {
  initMocks(this);
  cut = new ClassUnderTest(dep1, dep2);
}

在您的特定情况下，您应该模拟param1和param2。使用@InjectMocks时，切勿手动调用构造函数。

Answer 2

这可以通过遵循我的解决方案来解决

@ExtendWith(MockitoExtension.class)
public class EmployeeServiceTests {
    @Mock
    private EmployeeRepository repository;
    
    @InjectMocks
    private EmployeeService service = new EmployeeServiceImpl(repository); // need to declare an appropriate  constructor in the EmployeeServiceImpl , 
    
    private Employee employee;
    
    @Test
    public void whenSaveThenReturnSavedObject() {
        Employee employee = Employee.builder().firstName("Vineeth").lastName("A M").email("Myemail").build();
        Mockito.when(repository.save(employee)).thenReturn(employee);
        Employee savedEmp = service.saveEmployee(employee);
        assertEquals(savedEmp.getEmail(),employee.getEmail());
    }
}

@Service
public class EmployeeServiceImpl implements EmployeeService {

private EmployeeRepository employeeRepository;
    
    @Autowired
    public EmployeeServiceImpl(EmployeeRepository employeeRepository) {
    super();
    this.employeeRepository = employeeRepository;
}

    @Override
    public Employee saveEmployee(Employee obj) {
        Employee employee = employeeRepository.save(obj);
        return employee;
    }
}

Answer 3

要用依赖对象测试服务类，可以执行以下操作：

• 将@ExtendWith（SpringExtension.class）注释放在您的测试类上，而不是@ExtendedWith（MockitoExtension.calass）
• 把@SpringBootTest放到你的测试课上
• 将@Autowired注释放在任何依赖对象上，而不是@Mock

测试类别：

@ExtendWith（SpringExtension.class）@SpringBootTest公共类MyServiceTest{MyService MyService；@自动连线DependentObject DependentObject；@BeforeEach无效设置（）{myService=新的myService（dependentObject）；}

服务类别：

@服务公共类MyService{private DependentObject DependentObject；公共MyService（DependentObject DependentObject）｛｝}