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

Here an example ViewAssertion to check RecyclerView item count

public class RecyclerViewItemCountAssertion implements ViewAssertion {
  private final int expectedCount;

  public RecyclerViewItemCountAssertion(int expectedCount) {
    this.expectedCount = expectedCount;
  }

  @Override
  public void check(View view, NoMatchingViewException noViewFoundException) {
    if (noViewFoundException != null) {
        throw noViewFoundException;
    }

    RecyclerView recyclerView = (RecyclerView) view;
    RecyclerView.Adapter adapter = recyclerView.getAdapter();
    assertThat(adapter.getItemCount(), is(expectedCount));
  }
}

and then use this assertion

onView(withId(R.id.recyclerView)).check(new RecyclerViewItemCountAssertion(5));

I have started to write an library which should make testing more simple with espresso and uiautomator. This includes tooling for RecyclerView action and assertions. https://github.com/nenick/espresso-macchiato See for example EspRecyclerView with the method assertItemCountIs(int)