Add min-selector-uniqueness-ratio and min-declaration-uniqueness-ratio rules

[bartveneman]

Summary

This PR adds two new stylelint rules to the plugin that enforce minimum uniqueness ratios for selectors and declarations in CSS stylesheets.

Key Changes

• New Rule: min-selector-uniqueness-ratio - Enforces a minimum ratio of unique selectors to total selectors. Counts individual selectors in selector lists separately (e.g., a, b counts as 2 selectors).
• New Rule: min-declaration-uniqueness-ratio - Enforces a minimum ratio of unique declarations to total declarations. Uniqueness is determined by the combination of property and value.
• Added comprehensive test suites for both rules covering:
  • Invalid configuration handling (negative values, values > 1)
  • Edge cases (empty stylesheets, all unique declarations/selectors)
  • Boundary conditions (ratio exactly at limit)
  • Error scenarios (ratio below limit)
  • Special cases (selector lists, config value of 0 and 1)
• Updated the main plugin index to export both new rules
• Added both rules to the recommended configuration with sensible defaults (0.66 for selectors, 0.5 for declarations)

Implementation Details

• Both rules validate that the configuration value is a finite number between 0 and 1 (inclusive), and skip execution for invalid values
• Selectors are trimmed and counted individually from selector lists
• Declarations are uniquely identified by the combination of property and trimmed value
• Rules report errors at the root node with descriptive messages showing the actual ratio vs. required ratio
• Both rules include metadata with links to their documentation

https://claude.ai/code/session_01VURzQkGPNVKAvhiRHoNudb

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.11%. Comparing base (23c10dd) to head (2083842).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #85      +/-   ##
==========================================
+ Coverage   97.97%   98.11%   +0.13%     
==========================================
  Files          28       30       +2     
  Lines         792      847      +55     
  Branches      216      232      +16     
==========================================
+ Hits          776      831      +55     
  Misses         13       13              
  Partials        3        3              

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[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 3.33kB (6.1%) ⬆️⚠️, exceeding the configured threshold of 5%.

Bundle name	Size	Change
stylelintPlugin-esm	57.9kB	3.33kB (6.1%) ⬆️⚠️

Affected Assets, Files, and Routes:

view changes for bundle: stylelintPlugin-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
index.mjs	3.09kB	53.97kB	6.08% ⚠️
configs/recommended.d.mts	123 bytes	1.49kB	8.99% ⚠️
configs/recommended.mjs	112 bytes	1.4kB	8.72% ⚠️

Files in index.mjs:

• ./src/rules/min-declaration-uniqueness-ratio/index.ts → Total Size: 1.43kB

• ./src/index.ts → Total Size: 906 bytes

• ./src/rules/min-selector-uniqueness-ratio/index.ts → Total Size: 1.5kB

Files in configs/recommended.mjs:

• ./src/configs/recommended.ts → Total Size: 1.35kB