feat: Make par_names a _ModelConfig property attribute

[matthewfeickert]

Description

Resolves #1700

Make pyhf.pdf._ModelConfig.par_names() a property attribute to match the pyhf.pdf._ModelConfig.par_order API.

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• Tests are passing
• "WIP" removed from the title of the pull request
• Selected an Assignee for the PR to be responsible for the log summary

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* Make pyhf.pdf._ModelConfig.par_names() property attribute pyhf.pdf._ModelConfig.par_names,
  like the the pyhf.pdf._ModelConfig.par_order API.
* Update all usage of `.par_names()` to `par_names`.
* Use unittest.mock.PropertyMock to properly mock par_names return.

[matthewfeickert]

@kratsg @lukasheinrich while adding the

>>> import pyhf
>>> model = pyhf.simplemodels.correlated_background(
...     signal=[12.0, 11.0],
...     bkg=[50.0, 52.0],
...     bkg_up=[45.0, 57.0],
...     bkg_down=[55.0, 47.0],
... )
>>> model.config.par_order
['correlated_bkg_uncertainty', 'mu']
>>> model.config.par_names()
['correlated_bkg_uncertainty', 'mu']

example to PR #1705 I noted there's a bit of an inconsistency here in API. Can we slip this in under the wire for v0.7.0?

[matthewfeickert]

@alexander-held This will hit cabinetry but can be easily patched with

git grep --name-only "par_names()" -- src/ | xargs sed -i 's/par_names()/par_names/g'

[alexander-held]

See #1700, I assume that will still go into 0.7?

[matthewfeickert]

See #1700

Nice. 😎

I assume that will still go into 0.7?

Unless people object to be messing around with the API this late. 😬

[matthewfeickert]

CI is failing as I forgot that because of PR #1536

pyhf/tests/test_optim.py

Lines 579 to 582 in cccbda1

	pdf.config.par_names = mocker.Mock(return_value=None)
	_, result = pyhf.infer.mle.fit(data, pdf, return_result_obj=True)
	assert 'minuit' in result
	assert result.minuit.parameters == ('x0', 'x1')

needs to get fixes now too. I think this requires use of unittest.mock.PropertyMock.

[codecov]

Codecov Report

Base: 98.29% // Head: 98.30% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (eae9660) compared to base (cccbda1).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2027   +/-   ##
=======================================
  Coverage   98.29%   98.30%           
=======================================
  Files          69       69           
  Lines        4529     4530    +1     
  Branches      738      738           
=======================================
+ Hits         4452     4453    +1     
  Misses         45       45           
  Partials       32       32           

Flag	Coverage Δ
contrib	27.52% <50.00%> (+0.01%)	⬆️
doctest	61.14% <100.00%> (+<0.01%)	⬆️
unittests-3.10	96.31% <100.00%> (+<0.01%)	⬆️
unittests-3.7	96.28% <100.00%> (ø)
unittests-3.8	96.33% <100.00%> (+<0.01%)	⬆️
unittests-3.9	96.35% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pyhf/optimize/mixins.py	100.00% <100.00%> (ø)
src/pyhf/pdf.py	98.03% <100.00%> (+<0.01%)	⬆️

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[matthewfeickert]

Relevant RTD build: https://pyhf--2027.org.readthedocs.build/en/2027/_generated/pyhf.pdf._ModelConfig.html#pyhf.pdf._ModelConfig.par_names