Is there any point Unit testing serialization?

Question

I have a class that serializes a set of objects (using XML serialization) that I want to unit test.

My problem is it feels like I will be testing the .NET implementation

Answer 1

If you want to ensure that the serialization of your objects doesn't break, then by all means unit test. If you read the MSDN docs for the XMLSerializer class:

The XmlSerializer cannot serialize or deserialize the following:

Arrays of ArrayList
Arrays of List

There is also a peculiar issue with enums declared as unsigned longs. Additionally, any objects marked as [Obsolete] do no get serialized from .Net 3.5 onwards.

If you have a set of objects that are being serialized, testing the serialization may seem odd, but it only takes someone to edit the objects being serialized to include one of the unsupported conditions for the serialisation to break.

In effect, you are not unit testing XML serialization, you are testing that your objects can be serialized. The same applies for deserialization.