I agree that my original name proposal is terrible. :-)  method_check and verify_full_api both look fine to me.

> If all collection registrations were bundled together in 
> collections.py, I think I would expect the tests to be in 
> test_collections. But I could still be presuaded that the range method
> check should be in test_range where all the individual methods are 
> (should be!) tested.

All of the registrations are bundled together in _abcoll.py, which collections.py imports into collections.py's namespace.  (It's in a separate file to get around some bootstrapping issues.)

I favor putting them in test_collections to make it slightly easier to check for a 1:1 correlation between registrations and tests, but it's not something I feel strongly about.