### Question:
FlashMessagesView implements FlashMessages.View { @Override public void hideErrorContainer() { hide(errorContainer); } @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 testHideErrorContainer() { errorContainer.classList = mock(DOMTokenList.class); view.hideErrorContainer(); verify(errorContainer.classList).remove(OPENED_CONTAINER_CSS_CLASS); }