### Question:
HiddenHelper { public static boolean isHidden(final Element element) { return element.classList.contains(HIDDEN_CSS_CLASS); }  static void hide(final Element element); static void show(final Element element); static boolean isHidden(final Element element); static final String HIDDEN_CSS_CLASS; }### Answer:
@Test public void testIsHiddenWhenElementIsHidden() { final Element element = mock(Element.class); final DOMTokenList classList = mock(DOMTokenList.class); element.classList = classList; when(classList.contains(HIDDEN_CSS_CLASS)).thenReturn(true); assertTrue(HiddenHelper.isHidden(element)); }
@Test public void testIsHiddenWhenElementIsNotHidden() { final Element element = mock(Element.class); final DOMTokenList classList = mock(DOMTokenList.class); element.classList = classList; when(classList.contains(HIDDEN_CSS_CLASS)).thenReturn(false); assertFalse(HiddenHelper.isHidden(element)); }