Couple of points to discuss/agree upon before we can implement that:

• which scope to we want to support? test method only? test class? methods including ctor and fixture methods?
• for test methods, do we want to make the attribute a data source provider? So that when specifying multiple cultures the test would be run multiple times, each with a culture.
• given @mika76 suggestion, we would probably go for a single attribute. Do we want to have some properties or something to allow the attribute to set only one of the 2 (Culture vs UICulture) or is it mainly pointless?

Shoo a lot of time has passed since I posted this so I can't remember what I needed it for exactly, but off the top of my head...

1. At least methods but class could be quite useful. Really not sure about ctor and fixture methods.
2. I love this idea - when working with a codebase for an international audience (in my case in Serbia we even have 2 different alphabets) so being able to test multi cultures with one test sounds great!
3. I personally always use them both together so I would have said one method, but there are times I guess when you want to set one or the other only. If you have 2 they would mostly be copies of each other anyway. So I guess either 2 or make sure you can set them independently if single method.

Oh thanks for taking some time to give us your feedback @mika76 <3

That sounds like the best compromise, setting both at the same time, with extra option to set UI separately.

[TestCulture("cs-CZ")]
[TestCuture("cs-CZ", UICulture = "jp-JP")]  // change UI to something different
[TestCulture("en-US", UICulture = "jp-JP")] // "keep" en-US which is my current culture, and change the UI