### Question:
AbstractPopoverViewImpl implements PopoverView { @Override public void setOnClosedByKeyboardCallback(final Consumer<CanBeClosedByKeyboard> callback) { closedByKeyboardCallback = Optional.ofNullable(callback); } protected  AbstractPopoverViewImpl();  AbstractPopoverViewImpl(final Div popoverElement,
                                   final Div popoverContentElement,
                                   final JQueryProducer.JQuery<Popover> jQueryPopover); @Override void setOnClosedByKeyboardCallback(final Consumer<CanBeClosedByKeyboard> callback); @Override void show(final Optional<String> popoverTitle); @Override void hide(); boolean isVisible(); void keyDownEventListener(final Object event); boolean isEscapeKeyPressed(final KeyboardEvent event); boolean isEnterKeyPressed(final KeyboardEvent event); void onClosedByKeyboard(); Optional<Consumer<CanBeClosedByKeyboard>> getClosedByKeyboardCallback();  }### Answer:
@Test public void testSetOnClosedByKeyboardCallback() { final Consumer consumer = mock(Consumer.class); view.setOnClosedByKeyboardCallback(consumer); final Optional<Consumer<CanBeClosedByKeyboard>> actual = view.getClosedByKeyboardCallback(); assertTrue(actual.isPresent()); assertEquals(consumer, actual.get()); }