update-gem

name	update-gem
description	Checklist of files to update when adding or updating a rubocop plugin gem
allowed-tools	Read, Grep, Glob

When adding a new rubocop plugin gem or updating an existing gem version, the following files must be updated. Use this checklist to ensure nothing is missed.

Files to update

1. bench/corpus/Gemfile

Pin the gem version (e.g. gem "rubocop-rake", "0.7.1").

2. bench/corpus/diff_results.py

Add or update the gem version in the "baseline" dictionary inside write_corpus_results().

3. bench/corpus/baseline_rubocop.yml

Add the gem to the plugins: list. If any cops are Enabled: false in the gem's vendor default config, add explicit Enabled: true overrides (see existing examples for RSpec, Rails, etc.). Cops that default to Enabled: true or Enabled: pending don't need overrides — NewCops: enable handles pending cops.

4. bench/corpus/update_readme.py

Add an entry to the GEMS list with key, url, and departments.

5. scripts/dispatch_cops.py

Add the department to DEPT_TO_VENDOR (maps department name to vendor/<gem-dir>). If the department name doesn't snake_case cleanly (e.g. FactoryBot -> factory_bot, RSpecRails -> rspec_rails), also add it to DEPT_TO_DIR and DEPT_TO_SRC_DIR.

6. .github/workflows/batch-dispatch.yml

Add the department to the department choice options list (keep alphabetical order).

7. Vendor submodule

Add the vendor submodule pinned to the release tag: git submodule add <repo-url> vendor/<gem-name>.

8. Tier gating (no action needed)

New cops default to preview tier via src/resources/tiers.json. Promotion to stable happens automatically via the corpus oracle workflow — do not manually edit tiers.json. The corpus oracle uses --preview so preview-tier cops are always tested in CI, but users running nitrocop locally without --preview won't see them.

Reference

See PR #1353 (rubocop-rake support) for an example of adding a new plugin gem, though note it missed several of the items in this checklist (fixed in a follow-up commit).

Verification

After making changes, run:

uv run ruff check bench/corpus/diff_results.py scripts/dispatch_cops.py bench/corpus/update_readme.py