public void TestTryGetValue()
 {
     var wrapper = new BsonDocumentWrapper(new BsonDocument("x", 1));
     Assert.AreEqual(false, wrapper.IsMaterialized);
     BsonValue value;
     var result = wrapper.TryGetValue("x", out value);
     Assert.AreEqual(true, wrapper.IsMaterialized);
     Assert.AreEqual(true, result);
     Assert.AreEqual(new BsonInt32(1), value);
 }