Match background color of listview row Espresso

Question

I have a ListView with rows of different colors created through a custom adapter like:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;

    convertView = mInflater.inflate(R.layout.row_unit, parent, false);

    // ...

    if( /* some condition */ ) {
        convertView.setBackgroundColor(Color.LTGRAY);
    } else {
        convertView.setBackgroundColor(Color.WHITE);
    }
    return convertView;
}

In a test, I would like to check whether a certain element in the list has Color LTGRAY. I created a custom matcher:

public static Matcher<Object> backgroundShouldHaveColor(int expectedColor) {
    return viewShouldHaveBackgroundColor(equalTo(expectedColor));
}
private static Matcher<Object> viewShouldHaveBackgroundColor(final Matcher<Integer> expectedObject) {
    final int[] color = new int[1];
    return new BoundedMatcher<Object, View>( View.class) {
        @Override
        public boolean matchesSafely(View view) {

            color[0] =((ColorDrawable) view.getBackground()).getColor();


            if( expectedObject.matches(color[0])) {
                return true;
            } else {
                return false;
            }
        }
        @Override
        public void describeTo(final Description description) {
            // Should be improved!
            description.appendText("Color did not match " + color[0]);
        }
    };
}

Trying to test with

onView(withText("itemtext")).check(matches(backgroundShouldHaveColor(Color.LTGRAY)));

I get a null pointer exception.

Answer 1

The following seems to work for me:

onView(withChild(withText("itemtext"))) // this matches the LinearLayout or row/convertview
      .check(matches(withBgColor(Color.LTGRAY)));

where the custom matcher is:

public static Matcher<View> withBgColor(final int color) {
    Checks.checkNotNull(color);
    return new BoundedMatcher<View, LinearLayout>(LinearLayout.class) {
        @Override
        public boolean matchesSafely(LinearLayout row) {
            return color == ((ColorDrawable) row.getBackground()).getColor();
        }
        @Override
        public void describeTo(Description description) {
            description.appendText("with text color: ");
        }
    };
}

This is for a three column listview where each row consists of a LinearLayout with 3 child TextViews. "withText("itemtext")" matches an element/TextView in the first column. Elements in this column are unique.