annotationlib: Improve test coverage

[dr-carlos]

Feature or enhancement

Proposal:

The existing test suite for annotationlib is good, but there is still a decent amount of line/branch coverage missing. coverage.py reports 75% coverage, but this is mostly the library is already imported somewhere in coverage.py, so all global statements are marked as 'missing'.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-141174: Improve ForwardRef test coverage #141175
• gh-141174: Improve annotationlib.call_annotate_function() test coverage #141176
• gh-141174: Improve annotationlib._Stringifier test coverage #141220
• gh-141174: Improve annotationlib.get_annotations() test coverage #141286