@Rule
public final ActivityTestRule<YourActivity> mActivityRule = new ActivityTestRule<>(YourActivity.class);

@Test
public void testSample(){
    if (getRVcount() > 0){
        onView(withId(R.id.our_recycler_view)).perform(RecyclerViewActions.actionOnItemAtPosition(0, click()));
    }
}

private int getRVcount(){
    RecyclerView recyclerView = (RecyclerView) mActivityRule.getActivity().findViewById(R.id.our_recycler_view);
    return recyclerView.getAdapter().getItemCount();
}

@Test
 fun mainActivityTest() {
    val yourRecycler = onView(
        allOf(

            childAtPosition(
                withClassName(`is`("androidx.constraintlayout.widget.ConstraintLayout")),
                0
            ),
            instanceOf(RecyclerView::class.java)
        )
    )
    yourRecycler.check { view, noViewFoundException ->
                noViewFoundException?.apply {
                    throw this
                }
                assertTrue(view is RecyclerView &&
                    view.adapter != null && view.adapter?.itemCount?:-1 > 0
                )

            }
    }