### Question:
ListItemViewCssHelper { public static void asDownArrow(final Element element) { element.classList.remove(RIGHT_ARROW_CSS_CLASS); element.classList.add(DOWN_ARROW_CSS_CLASS); }  static void asRightArrow(final Element element); static void asDownArrow(final Element element); static boolean isRightArrow(final Element element); static void asFocusedDataType(final Element element); static void asNonFocusedDataType(final Element element); static boolean isFocusedDataType(final Element element); static final String RIGHT_ARROW_CSS_CLASS; static final String DOWN_ARROW_CSS_CLASS; static final String FOCUSED_CSS_CLASS; }### Answer:
@Test public void testAsDownArrow() { final Element element = mock(Element.class); final DOMTokenList classList = mock(DOMTokenList.class); element.classList = classList; ListItemViewCssHelper.asDownArrow(element); verify(classList).add(DOWN_ARROW_CSS_CLASS); verify(classList).remove(RIGHT_ARROW_CSS_CLASS); }