[MAINT] Refactor test nifti label maskers

[Remi-Gau]

• Relates to simplify "complex" tests #3570

Changes proposed in this pull request:

• use existing fixtures
• add new fixtures
• parametrize tests
• extract tests for errors and warnings
• split long tests into independent tests

[github-actions]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.07%. Comparing base (abb80ff) to head (d4ad8cf).
Report is 34 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4333      +/-   ##
==========================================
+ Coverage   91.85%   92.07%   +0.21%     
==========================================
  Files         144      143       -1     
  Lines       16419    16496      +77     
  Branches     3434     3463      +29     
==========================================
+ Hits        15082    15188     +106     
+ Misses        792      760      -32     
- Partials      545      548       +3     

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ubuntu-latest_3.8_test_min	68.83% <ø> (?)
ubuntu-latest_3.9_test_plotting	91.91% <ø> (?)
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[bthirion]

LGTM overall, thx !

[bthirion]

LGTM then.

[man-shu]

IIUC, both atlas and mask would be resampled?

[Remi-Gau]

From the doc:

For example, if resampling_target is “data”, the atlas is resampled to the shape of the data if needed.

If it is “labels” then mask_img and images provided to fit() are resampled to the shape and affine of maps_img.

“None” means no resampling: if shapes and affines do not match, a ValueError is raised.

[Remi-Gau]

When the target is labels there is a check in the test to make sure the mask is resampled.

I don't see a test for the None case though so actually worth adding it.

[man-shu]

I see! So mask_img does not need to be resampled to data because it is applied to the labels_img (not the data). As mentioned here:
"Mask to apply to regions before extracting signals."

[man-shu]

Thanks!

[man-shu]

Merging!

[Remi-Gau]

Just realized that the test for some of the errors did not have a match= to make sure that they send the proper error message.

Will make a mini follow up PR

[man-shu]

Oops, did I merge too soon?

[Remi-Gau]

Oops, did I merge too soon?

no worries, I will send a follow up PR that should be smaller and also easier to review