Question: I am interested in your opinions on unittesting code that uses Corba to communicate with a server.

Would you mock the Corba objects? In Python that's sort of a pain in the ass because all the methods of Corba objects are loaded dynamically. So you're basically stuck with "mock anything".

Thanks!

Note:
I believe I have not made myself clear enough, so I'll try to give a somewhat more concrete example:

A web application needs to display a page containing data received from the server. It obtains the data by calling server\_pagetable.getData() and then formats the data, converts them to the correct python types (because Corba does not have e.g. a date type etc.) and finally creates the HTML code to be displayed.

And this is what I would like to test - the methods that receive the data and do all the transformations and finally create the HTML code.

I believe the most straightforward decision is to mock the Corba objects as they essentially comprise both the networking and db functionality (which ought not to be tested in unit tests). 

It's just that this is quite a lot of "extra work" to do - mocking all the Corba objects (there is a User object, a server session object, the pagetable object, an admin object etc.). Maybe it's just because I'm stuck with Corba and therefore I have to reflect the object hierarchy dictated by the server with mocks. On the other hand, it could be that there is some cool elegant solution to testing code using Corba that just did not cross my mind.

Answer: 
I would set up a test server, and do live tests on that. Unittesting can be tricky with network stuff, so it's best to keep it as real as possible. Any mocking would be done on the test server, for instance if you need to communicate to three different servers, it could be set up with three different IP addresses to play the role of all three servers.
I have got similar work to tackle but I probably will not write a test for implementation of CORBA objects or more specifically COM objects (implementation of CORBA). I have to write tests for work that uses these structures as oppose to the structures themselves (although I could land myself in that role too if I ask too many questions). In the end of the day, unittest is integration on a smaller scale so whenever I write tests I am always thinking of input and outputs rather than actual structures. From the way you have written your problem my concentration would be on the data of server\_pagetable.getData() and the output HTML without caring too much about what happens inbetween (because that is the code you are testing, you don't want to define the code in the test but ensure that output is correct). If you want to test individual functions inbetween then I would get mock data (essentially still data, so you can generate mock data rather than mock class if possible). Mocks are only used when you don't have parts of the full code and those functions needs some input from those parts of the code but as you are not interested in them or don't have them you simplify the interaction with them. This is just my opinion.