spy does not initialize objects fully with InstrumentationMemberAccessor

[aswath80]

With mockito-inline, spy objects are missing fields when spying on child classes whose base class constructor is private. The issue goes away when base class constructor is made default access or public.

public class MockitoInnerClassSpyTest {

    static class P1 {

        @Override
        public String toString() {
            return "P1";
        }
    }

    static class P2 {

        @Override
        public String toString() {
            return "P2";
        }
    }

    static class C {

        private final P1 p1;

        private C(final P1 p1) {
            this.p1 = p1;
        }

        public void print() {
            System.out.println("C: p1=" + p1);
        }

        private static class D
            extends C {

            private final P2 p2;

            D(final P1 p1, final P2 p2) {
                super(p1);
                this.p2 = p2;
            }

            @Override
            public void print() {
                super.print();
                System.out.println("D: p2=" + p2);
            }
        }
    }

    @Test
    void test() {
        final C.D d = new C.D(new P1(), new P2());
        d.print();
        final C.D spy = spy(d);
        System.out.println("------------ spy ---------------");
        spy.print();
    }
}

This prints

C: p1=P1
D: p2=P2
------------ spy ---------------
C: p1=P1
D: p2=null

p2 is non-null in original object but becomes null in the spy. This issue does not happen in mockito-core with ReflectionMemberAccessor. If the constructor of C is made default or public, the issue does not occur.

Versions:

Mockito-Inline : 4.10
JDK - 17

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[raphw]

Ah, after a bit of head scratching I figured it out.

We have a snippet of code that selects the super constructor to call from a constructor that is

MethodList<MethodDescription.InDefinedShape> constructors =
    instrumentedType
        .getSuperClass()
        .asErasure()
        .getDeclaredMethods()
        .filter(isConstructor().and(not(isPrivate())));

That visibility check is no longer correct with nestmates (Java 11+) where javac does no longer create bridge methods to give access to private constructors, but where the access right is registered as an attribute. isPrivate needed to be replaced with isAccessible where the access right is evaluated with respect to all available properties by Byte Buddy.

[raphw]

Fixed in #2948

[aswath80]

Thank you, that was quick!

[aswath80]

I see the merge to master, is there a 4.x version where I can get this fix ?

[raphw]

Unfortunately no, we don't have capacity to backport changes.

[aswath80]

I still need this to work on both Java 8 & 17 and so can't switch to 5.x. I guess the only option is to switch private access to default in the outer class until we can switch to 5.x.

[raphw]

If you make the constructor package-private, that's basically what javac did for you on 8.