Ignore "You are using [hist/kde] as a plot kind" warnings

[AdamOrmondroyd]

Description

Since the UserWarnings were added to prevent users from unintentionally using kde instead of kde_1d etc, the test suite has been (correctly) flagging up these warnings, affecting quality of life

Tests obviously won't pass until either #341 or #339 are merged.

Fixes # (issue)

Checklist:

• I have performed a self-review of my own code
• My code is PEP8 compliant (flake8 anesthetic tests)
• My code contains compliant docstrings (pydocstyle --convention=numpy anesthetic)
• New and existing unit tests pass locally with my changes (python -m pytest)
• I have added tests that prove my fix is effective or that my feature works
• I have appropriately incremented the semantic version number in both README.rst and anesthetic/_version.py

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (108d77c) 100.00% compared to head (a85e990) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #342   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           34        34           
  Lines         2858      2858           
=========================================
  Hits          2858      2858           

Files Changed	Coverage Δ
anesthetic/_version.py	100.00% <100.00%> (ø)

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[lukashergt]

These are warnings that I'd argue should pop up in the tests, so they should not be suppressed, and they should "affect our quality of life"...

The warnings are bound to go away eventually with #320, but until then they are a good reminder that we should eventually clean this up fully.

[AdamOrmondroyd]

I agree they will go away with #320 as it stands, but should they? Unless we actually make hist and kde inaccessible through anesthetic they will still "look odd"

[lukashergt]

I agree they will go away with #320 as it stands, but should they? Unless we actually make hist and kde inaccessible through anesthetic they will still "look odd"

Agreed, it is probably good to keep them, but that means that rather than just filtering them out of the tests, we should make them part of the tests, i.e. make use of with pytest.warns(UserWarning):.

I see two ways of implementing this:

1. Change all the tests that currently are filtering the warnings out to instead make use of pytest.warns in the appropriate cases.
2. Keep the filtering as is, but add specific tests for the warnings.

What would others think best?

[AdamOrmondroyd]

Seeing as the filters don't appear that many times in the test suite, I think 1

Edit: ends up being a bit awkward since pytest.warns is a context, so contextlib.nullcontext is required to avoid repeating

[lukashergt]

This looks good, thanks @AdamOrmondroyd. Please, squash and merge if you think it is ready. And please feel free to hit "request review" to get a faster reaction from me.