Architecture-components-samples: AutoClearedValue cleans reference on Destroy of other fragment

[roybrener]

onFragmentViewDestroyed is being called even if the Fragment that is being destroyed is not the Holding Fragment. For Example - From the Base Fragment, open a DialogFragment

DialogFragment fragment = new SomeFragment();
fragment.show(getFragmentManager(), "tag");

On coming back from the Dialog Fragment, All AutoClearedView instances will get cleared in the Base Fragment. add same instance check on the Fragment solves the issue

[yigit]

That looks like a bug in the fragments library, we only observe the given fragment, not sub fragments. Can you please report a bug in issuetracker.google.com ?
Meanwhile, I'll fix this inside the project.

[yigit]

I added a test for this, does not seem to be broken.
https://github.com/googlesamples/android-architecture-components/pull/79/files

[thaihuynhxyz]

@yigit
Because of your test missing dismiss before assert testFragment.testValue.get() with "foo"
Test should be:

   @Test
    public void testDontClearForDialog() throws Throwable {
        testFragment.testValue = new AutoClearedValue<>(testFragment, "foo");
        DialogFragment dialogFragment = new DialogFragment();
        dialogFragment.show(testFragment.getFragmentManager(), "dialog");
        dialogFragment.dismiss();
        InstrumentationRegistry.getInstrumentation().waitForIdleSync();
        assertThat(testFragment.testValue.get(), is("foo"));
    }

Can we fix this bug with check the fragment that is destroyed view is the fragment registerFragmentLifecycleCallbacks?

    public AutoClearedValue(Fragment fragment, T value) {
        FragmentManager fragmentManager = fragment.getFragmentManager();
        fragmentManager.registerFragmentLifecycleCallbacks(
                new FragmentManager.FragmentLifecycleCallbacks() {
                    @Override
                    public void onFragmentViewDestroyed(FragmentManager fm, Fragment f) {
                        if(fragment == f) {
                            AutoClearedValue.this.value = null;
                            fragmentManager.unregisterFragmentLifecycleCallbacks(this);
                        }
                    }
                },false);
        this.value = value;
    }
}

[yigit]

you are right, sorry about that.

I've updated the PR and also reported here: https://issuetracker.google.com/issues/63514149

[yigit]

ok looks like it was a bad assumption on my side. since we are observing the fragment manager (not the fragment itself), we need to check the fragment instance.
thanks for the report.