我的代码抛出 java.lang.IllegalArgumentException: Matching real methods not found for the following mocks 错误

如何解决我的代码抛出 java.lang.IllegalArgumentException: Matching real methods not found for the following mocks 错误

我在下面的代码中做错了什么？有人可以提出建议吗。

@RunWith(JUnit4.class)
class testingClasstest {

//Added annotations on the classes

    @InjectMocks
    private TestingClass testClassObj;
    @Mock
     DO dO;
     private Exception ex;

    @Before
     public void setup() {
        MockitoAnnotations.initMocks(this);
        dO = new DO();
     }


//method to be tested

    @Test
    void testProcess() {
       dO = new dO();
        ex = new MyException(new ArrayList<>(),null);
        new MockUp<Mockingclass>() {
            @mockit.Mock
            public void method(Object obj,String st,Exception ex,String msg,ObjectConfig obj) {
                dO.setCd(Interfacecontaingconst.CD);
            }
        };
        testObj.method(DO,"6",ex,null,null);
        Assert.assertEquals(139,dO.getCd());
    }
}