Source for https://medium.com/p/3f6f4179652e - "RecyclerView and espresso, a complicated story"

MyTest.java

RecyclerViewInteraction.<Item>onRecyclerView(withId(R.id.recyclerview))
    .withItems(items)
    .check(new ItemViewAssertion<Item>() {
        @Override
        public void check(Item item, View view, NoMatchingViewException e) {
            matches(hasDescendant(withText(item.getDisplayName())))
                .check(view, e);
        }
    });

RecyclerItemViewAssertion.java

import android.support.test.espresso.NoMatchingViewException;
import android.support.test.espresso.PerformException;
import android.support.test.espresso.ViewAssertion;
import android.support.test.espresso.util.HumanReadables;
import android.support.v7.widget.RecyclerView;
import android.view.View;

public class RecyclerItemViewAssertion<A> implements ViewAssertion {

    private int position;
    private A item;
    private ItemViewAssertion<A> itemViewAssertion;

    public RecyclerItemViewAssertion(int position, A item, ItemViewAssertion<A> itemViewAssertion) {
        this.position = position;
        this.item = item;
        this.itemViewAssertion = itemViewAssertion;
    }

    @Override
    public final void check(View view, NoMatchingViewException e) {
        RecyclerView recyclerView = (RecyclerView) view;
        RecyclerView.ViewHolder viewHolderForPosition = recyclerView.findViewHolderForLayoutPosition(position);
        if (viewHolderForPosition == null) {
            throw (new PerformException.Builder())
                    .withActionDescription(toString())
                    .withViewDescription(HumanReadables.describe(view))
                    .withCause(new IllegalStateException("No view holder at position: " + position))
                    .build();
        } else {
            View viewAtPosition = viewHolderForPosition.itemView;
            itemViewAssertion.check(item, viewAtPosition, e);
        }
    }
}

RecyclerViewInteraction.java

import android.support.test.espresso.NoMatchingViewException;
import android.view.View;

import org.hamcrest.Matcher;

import java.util.List;

import static android.support.test.espresso.Espresso.onView;
import static android.support.test.espresso.contrib.RecyclerViewActions.scrollToPosition;

public class RecyclerViewInteraction<A> {

    private Matcher<View> viewMatcher;
    private List<A> items;

    private RecyclerViewInteraction(Matcher<View> viewMatcher) {
        this.viewMatcher = viewMatcher;
    }

    public static <A> RecyclerViewInteraction<A> onRecyclerView(Matcher<View> viewMatcher) {
        return new RecyclerViewInteraction<>(viewMatcher);
    }

    public RecyclerViewInteraction<A> withItems(List<A> items) {
        this.items = items;
        return this;
    }

    public RecyclerViewInteraction<A> check(ItemViewAssertion<A> itemViewAssertion) {
        for (int i = 0; i < items.size(); i++) {
            onView(viewMatcher)
                    .perform(scrollToPosition(i))
                    .check(new RecyclerItemViewAssertion<>(i, items.get(i), itemViewAssertion));
        }
        return this;
    }

    public interface ItemViewAssertion<A> {
        void check(A item, View view, NoMatchingViewException e);
    }
}

Can you please show the implementation of these with a little of details?

@romainpiel nice medium article. BTW, what is the license on this code snippet