public void BackpatchSize_should_throw_when_size_is_larger_than_2GB() { using (var stream = new NullBsonStream()) using (var binaryWriter = new BsonBinaryWriter(stream)) { var bytes = new byte[int.MaxValue / 2]; // 1GB var binaryData = new BsonBinaryData(bytes); binaryWriter.WriteStartDocument(); binaryWriter.WriteName("array"); binaryWriter.WriteStartArray(); binaryWriter.WriteBinaryData(binaryData); binaryWriter.WriteBinaryData(binaryData); Action action = () => binaryWriter.WriteEndArray(); // indirectly calls private BackpatchSize method action.ShouldThrow <FormatException>(); } }