public void PreventsDuplicates()
{
var suspensionContext = new SuspensionContext();
suspensionContext.Add(null);
suspensionContext.Add(string.Empty);
suspensionContext.Add("A");
suspensionContext.Add("A");
var items = suspensionContext.Properties.ToList();
Assert.AreEqual(2, items.Count);
Assert.AreEqual(string.Empty, items[0]);
Assert.AreEqual("A", items[1]);
}
}