如何在 Mockito 参数捕获器中多次捕获相同的 object

Question

I was writing a Junit to test a scenario where an object changes its variables and saves it into the database 2 times. The argumentCaptor is invoked in save operation. The getAllValues() is returning two records. But both values are referenced to the same last capture record.

ImplimentationClass.java

 ...

myObj.setVariable(oneValue);
saveMyObj(myObj);
myObj.setVariable(otherValue);
saveMyObj(myObj);

...

saveMyObj(MyObject myObj){
repository.save(myObj);
}

ImplimentationClassTest.java

private ImplimentationClass underTest ;

@Mock
private Repository mockRepository;

@Before
public void setup(){
  initMocks(this);
  underTest = new ImplimentationClassTest();
}

@Test
public void test(){
ArgumentCaptor<MyObject> captor = ArgumentCaptor.forClass(MyObject.class);
MyObject obj = new MyObject(value);
underTest.implementedMethod(obj);
verify(mockRepository, times(2)).save(captor.capture());
assertEquals(oneValue, captor.getAllValues().get(0).getVariable()); //failing here -getting otherValue
assertEquals(otherValue, captor.getAllValues().get(1).getVariable());

}

Any idea how to capture same object multiple times?

Answer 1

The problem from your test originates from this piece of code.

myObj.setVariable(oneValue);
saveMyObj(myObj);
myObj.setVariable(otherValue);
saveMyObj(myObj);

Once you change the variable inside of myObj you change it for all references. Note that the ArgumentCaptor does not make a deep copy of myObj . So you will end up with two references to myObj , which only has the latest state.

To avoid this you might want to pass a different instance to the second call.

---

Another alternative might be to use doAnswer instead and check the correctness of the paramter inside that method.

Check this answer for an example.