### Question:
Stages { public static CompletionStage<Stage> scheduleDisplaying(final Stage stage) { LOG.debug( "Requested displaying of stage {} with title : \"{}\"", stage, stage.getTitle() ); return FxAsync.doOnFxThread( stage, Stage::show ); } private  Stages(); static CompletionStage<Stage> stageOf(final String title, final Pane rootPane); static CompletionStage<Stage> scheduleDisplaying(final Stage stage); static CompletionStage<Stage> scheduleDisplaying(final CompletionStage<Stage> stageCreationResult); static CompletionStage<Stage> scheduleHiding(final Stage stage); static CompletionStage<Stage> scheduleHiding(final CompletionStage<Stage> stageCreationResult); static CompletionStage<Stage> setStylesheet(final Stage stage, final String stylesheet); static CompletionStage<Stage> setStylesheet(final CompletionStage<Stage> stageCreationResult, final String stylesheet); static CompletionStage<Stage> setStylesheet(final Stage stage, final FxmlStylesheet stylesheet); static CompletionStage<Stage> setStylesheet(final CompletionStage<Stage> stageCreationResult, final FxmlStylesheet stylesheet);  }### Answer:
@Test public void scheduleDisplaying() throws ExecutionException, InterruptedException { Stages.scheduleDisplaying(testStage) .thenAccept(stage -> assertThat(testStage.isShowing()).isTrue()) .toCompletableFuture().get(); }