public void TestFindOneById()
{
_collection.RemoveAll();
var id = ObjectId.GenerateNewId();
_collection.Insert(new BsonDocument { { "_id", id }, { "x", 1 }, { "y", 2 } });
var result = _collection.FindOneById(id);
Assert.AreEqual(1, result["x"].AsInt32);
Assert.AreEqual(2, result["y"].AsInt32);
}