public Window getDialog(String caption) {
    List<Window> windows = this.fakeVaadinSession.getWindowsAdded();
    List<Window> collect = windows.stream().filter(w -> caption.equals(w.getCaption())).collect(Collectors.toList());
    Optional<Window> window = Optional.of(collect.get(collect.size() - 1));
    // TODO Currently I am getting the last opened dialog regardless if it was closed or not.
    //  Ensure closed dialogs are removed from the session.
    //  Do not allow dialogs with same name to be opened if one such exists.
    //  To get failing tests replace the above with
    //  Optional<Window> window = windows.stream().filter(w -> caption.equals(w.getCaption())).findFirst();
    return window.orElseThrow(() -> new RuntimeException("Not found window with caption " + caption));
}