TEST: Use class variables and close open file handles in ECAT tests

[DimitriPapadopoulos]

ResourceWarning: unclosed file <_io.BufferedReader name='/home/runner/work/nibabel/nibabel/virtenv/lib/python3.9/site-packages/nibabel/tests/data/tinypet.v'>

[codecov]

Codecov Report

Base: 92.38% // Head: 92.38% // No change to project coverage 👍

Coverage data is based on head (a33a2af) compared to base (d0e6363).
Patch has no changes to coverable lines.

❗ Current head a33a2af differs from pull request most recent head f0770b9. Consider uploading reports for the commit f0770b9 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1155   +/-   ##
=======================================
  Coverage   92.38%   92.38%           
=======================================
  Files          98       98           
  Lines       12257    12257           
  Branches     2520     2520           
=======================================
  Hits        11324    11324           
  Misses        612      612           
  Partials      321      321           

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[effigies]

Tests should be fixed if you rebase on master...

[DimitriPapadopoulos]

I am still getting errors, they seem related to CI instability.

[effigies]

Hmm. Looks like there might be a between-test dependency that can get broken by pytest-xdist. I ran several times and thought I would have caught a non-determinism...

[effigies]

Okay, let's try again...

[effigies]

This doesn't seem to have eliminated the warning.

[DimitriPapadopoulos]

Removing all warnings requires a rewrite of the testing classes.

In any case, this does the right thing by changing ecat_file → self.example_file.

[effigies]

Yeah, I think we need to move to a different fixture approach to ensure better handling of resources. Are you good to merge this as-is, or are there things you still want to try to do here?

[DimitriPapadopoulos]

I'm good, I can rewrite the commit message if needed.