All You Need To Know About Android Espresso Testing (Part IV)

Learn about Android Espresso Testing

2 minute read

Android Espresso Testing

In previous article, we talked about how to scroll to a certain position in RecyclerView in the test. In this article, we further discuss how to write a custom matcher and use it to scroll the RecyclerView.

Let’s say that we want to scroll to certain item in RecyclerView, but we don’t know the position. We can then create a custom Matcher, and use the matcher to determine which item to scroll to. We can write the matcher like this:

public class Matchers {

    public static Matcher<View> withTaskViewName(final String expected) {
        return new TypeSafeMatcher<View>() {
            @Override
            protected boolean matchesSafely(View item) {
                if (item != null && item.findViewById(R.id.task_item_task_name) != null) {
                    TextView taskName = (TextView) item.findViewById(R.id.task_item_task_name);
                    return !TextUtils.isEmpty(taskName.getText()) && taskName.getText().toString().equals(expected);
                } else {
                    return false;
                }
            }

            @Override
            public void describeTo(Description description) {
                description.appendText("Looked for " + expected + " in the task_item_layout.xml file");
            }
        };
    }
}

The matcher is rather simple, we just say that given a view, if we can find that there is a TextView with such and such id, and it contains such and such text, then we consider it a match, otherwise no match.

One thing to note is that we are not checking anyting in this test, this is because if the matcher doesn’t find a match, the scroll action will fail, so the test will fail.

Now the test becomes:

onView(withId(R.id.task_list)).perform(RecyclerViewActions.scrollTo(Matchers.withTaskViewName("task 10")));

Find the source code here.

~To be continued~

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