public void RemoveAll_SingleCollection()
{
var collection = new Dictionary<int, int> { { 1, 1 }, { 2, 2 }, { 3, 3 } };
Assert.IsTrue (collection.RemoveAll (kvp => kvp.Value == 2));
Assert.AreEqual (2, collection.Count);
Assert.IsFalse (collection.ContainsValue (2), "Collection still contains removed items");
}