JMockit mock private method in @PostConstruct

Question

Context

In my class under test there is a @PostConstruct annotated method that invokes another private method.

@PostConstruct
public void init() {
    longWork(); // private method
}

JMockit's default behaviour is to execute @PostConstruct methods of @Tested classes upon injection.

If a @Tested class has a method annotated with javax.annotations.PostConstruct, it should be executed right after injection.

https://github.com/jmockit/jmockit1/issues/13

Problem

JMockit calls the init() method, what I don't want.

From the thread dump:

at com.me.Worker.longWork(Worker.java:56)
at com.me.Worker.longWork.init(Worker.java:47)
...
at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:96)

How can that call be mocked/removed/blocked?

Attempts

I tried to mock the init and longWork methods as shown below. However that results in NullPointerException as sut is not injected yet.

@Before
public void recordExpectationsForPostConstruct()
{
    new NonStrictExpectations(sut) {{ invoke(sut, "init"); }};
}

Answer 1

You can try manually initializing your class to be tested without using @Tested. And then, set mock dependencies via setter methods (or using mockit.Deencapsulation.setField() method).

You can try something similar to this;

//Define your class under test without any annotation
private MyServiceImpl serviceToBeTested;

//Create mock dependencies here using @Mocked like below
@Mocked Dependency mockInstance;



@Before
public void setup() {
    //Initialize your class under test here (or you can do it while declaring it also). 
    serviceToBeTested = new MyServiceImpl();

    //Set dependencies via setter (or using mockit.Deencapsulation.setField() method)
    serviceToBeTested.setMyDependency(mockInstance);

    //Optionally add your expectations on mock instances which are common for all tests
    new Expectations() {{
        mockInstance.getName(); result = "Test Name";
        ...
    }};
}

@Test
public void testMyMethod(@Mocked AnotherDependency anotherMock) {
    //Add your expectations on mock instances specifics to this test method.
    new Expectations() {{
        mockInstance.getStatus(); result = "OK";
        anotherMock.longWork(); result = true;
        ...
    }};

    //Set dependencies via setter or using mockit.Deencapsulation.setField() method
    Deencapsulation.setField(serviceToBeTested, "myAnotherDep", anotherMock);

    //Invoke the desired method to be tested
    serviceToBeTested.myMethod();

    //Do the verifications & assertions
    new Verifications() {{
      ....
      ....

    }};

}

Answer 2

Perhaps you could delegate the longWork method to a different class and mock this one. Difficulties while writing tests is often a sign of design flaws