public void LowLevelGetAttributesOverrideTest()
 {
     using var storage   = new MyTextStorage("Hello World");
     using var container = new NSTextContainer {
               Size = new CGSize(100, float.MaxValue),
               WidthTracksTextView = true
           };
     using var layoutManager = new NSLayoutManager();
     layoutManager.AddTextContainer(container);
     storage.AddLayoutManager(layoutManager);
     layoutManager.EnsureLayoutForCharacterRange(new NSRange(0, 1));
     Assert.That(storage.LowLevelGetAttributes_Called, Is.GreaterThan(0), "LowLevelGetAttributes #called");
     Assert.That(storage.LowLevelValue_Called, Is.GreaterThan(0), "LowLevelValue #called");
 }