Fix a handful of regressions and issues in unit tests.
Review Request #12091 — Created Feb. 27, 2022 and submitted
Some recent changes, and updates to third-party tools, have regressed
some unit tests. This change fixes them up.
- A cookie-related error assertion that didn't work on all versions of
Python 2 and 3.
- Full-repository unit tests never cleaned up their temp directories.
- Modern versions of flake8 no longer report both styling errors and
syntax errors in our test file.
- RuboCop had a bad string check.
- RuboCop error message checks now check in a way that doesn't depend on
a given version of Ruby.
- Shellcheck error checks have been updated for string changes in the
All unit tests pass on Python 2.7 and 3.6-3.10 (except Infer, which I
can't yet test on Apple M1).