Hello Conrad,
I've had similar situations in the past.
At the moment we don't have platform specific jUnit tests. Instead the existing jUnits are ran against win/cocoa/gtk versions of gtk.
We've been brainstorming some ideas on the subject. For example one solution might be to add separate projects:
org.eclipse.swt.tests.gtk
org.eclipse.swt.tests.win32
org.eclipse.swt.tests.cocoa
(sort of like we have separate projects for binaries)
This would be pretty straight forward and easy to understand at first glance (no need to mess with .classpath etc..).
It's easy to add them if we don't need Hudson to test them. E.g only run them on demand by the developer.
However, if Hudson is involved, then things get a bit complicated as we'd need to fiddle around with Hudson configurations.
We could start off with just having separate projects as above and put tests in there, and not have them tested by Hudson for now. Then later if we have maybe more than 50-100 tests, look into actually incorporating them into Hudson.
Thoughts?
If we agree on the idea, I could look into adding such projects.