public void ShouldSyncItsContainerWithModelParents()
        {
            var model_a = new Model ("a");
            var model_b = new Model ("b");
            var model_container = new Model("container");
            var models = new ModelCollection(model_container);
            models.AddRange(new [] {model_a, model_b});

            Assert.That(models.Container, Is.EqualTo(model_container));
            Assert.That(models.All(m => m.Parent == model_container));

            models.Clear();

            Assert.That(model_a.Parent, Is.Null);
            Assert.That(model_b.Parent, Is.Null);

            models.Add(model_a);

            Assert.That(model_a.Parent, Is.EqualTo(model_container));

            models.Insert(0, model_b);

            Assert.That(model_b.Parent, Is.EqualTo(model_container));

            models.Remove(model_a);

            Assert.That(model_a.Parent, Is.Null);
        }