Espresso RecyclerView count test

gistfile1.java

@Test
    public void FilterClickShouldChangeRecyclerViewCount() {
        // Get items count before action
        RecyclerView recyclerView = mActivityTestRule.getActivity().findViewById(R.id.recycler_view);
        int countBefore = Objects.requireNonNull(recyclerView.getAdapter()).getItemCount();
        Log.e("count", "Items count before: " + countBefore);

        // Perform action
        ViewInteraction actionMenuItemView = onView(
                allOf(
                        withId(R.id.action_filter),
                        withContentDescription("Show Favorites")));
        actionMenuItemView.perform(click());

        // Verify that items count has changed
        onView(withId(R.id.recycler_view))
                // Instead of 'not', you can use any other hamcrest Matcher like 'is', 'lessThan' etc.
                .check(new RecyclerViewItemCountAssertion(not(countBefore)));
    }