public void TestRemoveAt()
{
var wrapper = new BsonDocumentWrapper(new BsonDocument { { "x", 1 }, { "y", 2 } });
Assert.AreEqual(false, wrapper.IsMaterialized);
wrapper.RemoveAt(1);
Assert.AreEqual(true, wrapper.IsMaterialized);
Assert.AreEqual(1, wrapper.ElementCount);
Assert.AreEqual("x", wrapper.GetElement(0).Name);
Assert.AreEqual(new BsonInt32(1), wrapper[0]);
}