Consider provided immutable classes for generic fields

[danielFesenmeyer]

When I have declared some class as immutable, I would expect that a class having a field of a generic subtype of this class is also considered as immutable.

But this does not work. The following test fails:

    @Test
    public void assertImmutability() {
        assertInstancesOf(ClassWithGenericField.class, areImmutable(),
                provided(SomeInterface.class).isAlsoImmutable());
    }


    private static final class ClassWithGenericField<T extends SomeInterface> {
        private final T field;

        public ClassWithGenericField(final T field) {this.field = field;}

        public T getField() {
            return field;
        }
    }

    private interface SomeInterface {

    }

[Grundlefleck]

Yup, I think that's a fair assessment.

I know it's not the same assertion, but this might be a workaround in the meantime:

assertInstancesOf(ClassWithGenericField.class, areImmutable(), provided("T").isAlsoImmutable());

I'm not sure if the generic type information is available to the isAlsoImmutable() matcher, but we definitely capture generic information, so might just be a case of storing it for access later. I'm afraid I've no ETA on this, just due to family+time commitments. How badly is it affecting you?

[danielFesenmeyer]

Thanks for the workaround :)

This is not urgent for us, it's more a nice-to-have.