### Question:
ListSelectorHeaderItemViewImpl implements ListSelectorHeaderItemView { @Override public void setIconClass(final String iconClass) { this.icon.getElement().setClassName(iconClass); } ListSelectorHeaderItemViewImpl(); @Inject  ListSelectorHeaderItemViewImpl(final Span text, final Icon icon); @Override void setText(final String text); @Override void setIconClass(final String iconClass);  }### Answer:
@Test public void testSetIconClass() { final String iconClass = "class"; final Element element = mock(Element.class); when(this.icon.getElement()).thenReturn(element); headerItemView.setIconClass(iconClass); verify(element).setClassName(iconClass); }