[FIX] Apply Ruff fix to rtest files.

[genedan]

Summary of Changes

Stacked PR on top of #1290. Added a missing function dev_corr_p - it was referenced later in the code but never defined.

Related GitHub Issue(s)

#1216

Additional Context for Reviewers

Checklist

• I passed tests locally for both code (uv run pytest) and documentation changes (uv run --directory docs jb build . --builder=custom --custom-builder=doctest)

---

Note

Low Risk
Test-only lint and a small missing helper in inactive @pytest.mark.r tests; no production library behavior changes.

Overview
Brings the optional R vs Python rtest_*.py modules in line with Ruff so their per-file ignores can be dropped from pyproject.toml.

Across those files, bare except: becomes except ImportError:, block-comment headers use single # instead of ###, unused imports are removed, and minor formatting/EOF fixes are applied. In rtest_correlation.py, adds the missing dev_corr_p helper (Python-side development_correlation) that downstream correlation tests already called but never defined.

^{Reviewed by Cursor Bugbot for commit 3edb51d. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

Pyright Type Completeness

View the full pyright --verifytypes output for this commit

Project (full chainladder package, at this PR's head): 15.4% of exported symbols fully typed (213 / 1382)

	Known	Ambiguous	Unknown	Total
Project (head)	213	110	1059	1382

Other symbols referenced but not exported by chainladder: 13

	Known	Ambiguous	Unknown	Total
Other (head)	3	1	9	13

Symbols without documentation:

• Functions without docstring: 327
• Functions without default param: 0
• Classes without docstring: 10

Patch (exported symbols added or changed by this PR): 0.0% fully typed (0 / 1)

	Known	Ambiguous	Unknown	Total
Patch	0	0	1	1

Patch symbol details

Symbol	Status	Change
chainladder.core.tests.rtest_correlation.dev_corr_p	❌ unknown	new

[codecov]

Codecov Report

❌ Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (gd_ruff_fix_user_guide@c56e176). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
chainladder/core/tests/rtest_correlation.py	0.00%	3 Missing ⚠️
chainladder/development/tests/rtest_clark.py	0.00%	1 Missing ⚠️
chainladder/development/tests/rtest_development.py	0.00%	1 Missing ⚠️
chainladder/development/tests/rtest_munich.py	0.00%	1 Missing ⚠️
chainladder/methods/tests/rtest_mack.py	0.00%	1 Missing ⚠️
chainladder/tails/tests/rtest_exponential.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                    Coverage Diff                    @@
##             gd_ruff_fix_user_guide    #1301   +/-   ##
=========================================================
  Coverage                          ?   91.69%           
=========================================================
  Files                             ?       93           
  Lines                             ?     5429           
  Branches                          ?      704           
=========================================================
  Hits                              ?     4978           
  Misses                            ?      326           
  Partials                          ?      125           

Flag	Coverage Δ
unittests	91.69% <0.00%> (?)

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[henrydingliu]

ldf_ is always np. sp.allclose also doesn't exist.

[henrydingliu]

ldf_ is always np. sp.testing.assert_array_equal also doesn't exist.