Convert test_cartography, test_cdm, test_cell to PyTest

[trexfeathers]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.95%. Comparing base (09feafe) to head (07744a4).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6609   +/-   ##
=======================================
  Coverage   89.95%   89.95%           
=======================================
  Files          91       91           
  Lines       24447    24447           
  Branches     4567     4567           
=======================================
  Hits        21992    21992           
  Misses       1686     1686           
  Partials      769      769           

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[ESadek-MO]

A couple of bad patterns.

Note that some of these patterns I've only commented on one, but appear multiple times, throughout multiple files! Also, in some files, the pytest.raises is fine in places, but wrong in others. I'd double check the whole file just to make sure it's not inconsistent.

[ESadek-MO]

One thing came up in the checklist, it's minor, I'm just using this PR to agree a policy on things like this.

[ESadek-MO]

Thanks @trexfeathers!

For future reference, we decided offline that if it's an easy change, we should do our best to enforce small consistency rules (such as _setup(self), for neatness etc.