How to count RecyclerView items with Espresso

Question

Using Espresso and Hamcrest,

How can I count items number available in a recyclerView?

Exemple: I would like check if 5 items are displaying in a specific Re

Answer 1

You can create a custom BoundedMatcher:

object RecyclerViewMatchers {
    @JvmStatic
    fun hasItemCount(itemCount: Int): Matcher {
        return object : BoundedMatcher(
            RecyclerView::class.java) {

            override fun describeTo(description: Description) {
                description.appendText("has $itemCount items")
            }

            override fun matchesSafely(view: RecyclerView): Boolean {
                return view.adapter.itemCount == itemCount
            }
        }
    }
}

And then use it like this:

onView(withId(R.id.recycler_view)).check(matches((hasItemCount(5))))