tests: various small changes/refactors
Some changes to tests that are more internal changes, with almost no actual behaviour change:
- use more pytest bits for parameters, and marking IDs
- move the
requests
handling as fixture, improving it to share it even more- this is the only behaviour change: the
requests.Session
object is now shared across all the OSes; this should make the test a bit faster (by virtue of more connection reuse)
- this is the only behaviour change: the
- add the own URL type for kernels, with no content-types for it (none is reported)