How to check if recyclerView is empty Espresso

Question

How can I check if my recyclerview is empty using espresso?

I know I can check if it has elements by clicking on element position but I want start my test by checking if it is empty.

@RunWith(AndroidJUnit4ClassRunner::class)
class TagsFragmentTest {
    @Rule
    @JvmField
    var repeatRule: RepeatRule = RepeatRule()

    @get:Rule
    var activityScenarioRule = activityScenarioRule<LoginActivity>()

    @Test
    @RepeatTest(1)
    fun test_checkTags() {
        //check main activity
        Thread.sleep(5000);
        onView(withId(R.id.mainFragmentManager)).check(matches(isDisplayed()))
        //go to Tags fragment
        onView(withId(R.id.nav_tags)).check(matches(isDisplayed()))
        onView(withId(R.id.nav_tags)).perform(click())

       //CHECK MY RECYCLERVIEW IS EMPTY
       //ADD TAGS
       //CHECK IF HAS TAGS
    }

}

Answer 1

I created a custom ViewMatcher:

fun recyclerViewSizeMatcher(matcherSize: Int): Matcher<View?>? {
    return object : BoundedMatcher<View?, RecyclerView>(RecyclerView::class.java) {
        override fun describeTo(description: Description) {
            description.appendText("with list size: $matcherSize")
        }

        override fun matchesSafely(recyclerView: RecyclerView): Boolean {
            return matcherSize == recyclerView.adapter!!.itemCount
        }
    }
}

that checks if the adapter.itemCount has the passed elements.

You could use it as:

recyclerViewSizeMatcher(0)

in that case it has to be empty (0 elements).