Exclude tests from coverage

[DimitriPapadopoulos]

Tests files shouldn't be examined for coverage, should they?

TODO:

• Unit tests and/or doctests in docstrings
• Tests pass locally
• Docstrings and API docs for any new/modified user-facing classes and functions
• Changes documented in docs/release.rst
• Docs build locally
• GitHub Actions CI passes
• Test coverage to 100% (Codecov passes)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.80%. Comparing base (07755d1) to head (2178321).
Report is 46 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #631      +/-   ##
==========================================
- Coverage   99.92%   99.80%   -0.12%     
==========================================
  Files          62       25      -37     
  Lines        2692     1031    -1661     
==========================================
- Hits         2690     1029    -1661     
  Misses          2        2              

see 37 files with indirect coverage changes

[dstansby]

What's the motivation for this? As far as I can tell it's good to include tests in code coverage, to make sure we're running them all.

[d-v-b]

seconding @dstansby, it's useful to know if we have dead code in our tests

[DimitriPapadopoulos]

My wrong, I was focused on the primary goal, coverage of library code. There are secondary goals, such as finding dead code in test code.

I would have split this test into two tests, coverage of library code and detection of dead code in test code, but that's probably over-engineering.