### Question:
FlashMessagesView implements FlashMessages.View { @EventHandler("cancel-warning-button") public void onCancelWarningButtonClick(final ClickEvent e) { presenter.executeErrorWarningCallback(); hideWarningContainer(); disableWarningHighlight(); } @Inject  FlashMessagesView(final HTMLDivElement errorContainer,
                             final HTMLDivElement warningContainer,
                             final @Named("strong") HTMLElement strongErrorMessage,
                             final @Named("span") HTMLElement regularErrorMessage,
                             final @Named("strong") HTMLElement strongWarningMessage,
                             final @Named("span") HTMLElement regularWarningMessage,
                             final HTMLButtonElement okWarningButton,
                             final HTMLButtonElement cancelWarningButton,
                             final HTMLButtonElement closeSuccessButton,
                             final HTMLDivElement successContainer,
                             final @Named("strong") HTMLElement strongSuccessMessage,
                             final @Named("span") HTMLElement regularSuccessMessage); @Override void init(final FlashMessages presenter); @EventHandler("close-success-message-button") void onCloseSuccessButtonClick(final ClickEvent e); @EventHandler("ok-warning-button") void onOkWarningButtonClick(final ClickEvent e); @EventHandler("cancel-warning-button") void onCancelWarningButtonClick(final ClickEvent e); @Override void showErrorMessage(final String strongMessage,
                                 final String regularMessage); @Override void showWarningMessage(final String strongMessage,
                                   final String regularMessage); @Override void showSuccessMessage(final String strongMessage,
                                   final String regularMessage); @Override void showErrorHighlight(final String errorElementSelector); @Override void showWarningHighlight(final String warningElementSelector); @Override boolean isElementPresent(final String elementSelector); @Override void hideWarningContainer(); @Override void hideSuccessContainer(); @Override void hideErrorContainer();  }### Answer:
@Test public void testOnCancelWarningButtonClick() { final ClickEvent event = mock(ClickEvent.class); doNothing().when(view).disableWarningHighlight(); warningContainer.classList = mock(DOMTokenList.class); view.onCancelWarningButtonClick(event); verify(presenter).executeErrorWarningCallback(); verify(warningContainer.classList).remove(OPENED_CONTAINER_CSS_CLASS); verify(view).disableWarningHighlight(); }