DataSetDefExplorerScreen { void onErrorEvent(@Observes ErrorEvent errorEvent) { checkNotNull("errorEvent", errorEvent); if (errorEvent.getClientRuntimeError() != null) { showError(errorEvent.getClientRuntimeError()); } else if (errorEvent.getMessage() != null) { showError(errorEvent.getMessage()); } }  @OnStartup void onStartup(PlaceRequest placeRequest); @OnClose void onClose(); @WorkbenchPartTitle String getTitle(); @WorkbenchPartView IsWidget getView(); @WorkbenchMenu Menus getMenu();  }
@Test public void testOnErrorEvent() { final ErrorEvent errorDataSetEvent = mock(ErrorEvent.class); when(errorDataSetEvent.getMessage()).thenReturn("errorMessage"); presenter.onErrorEvent(errorDataSetEvent); verify(errorPopupPresenter, times(1)).showMessage("errorMessage"); }