`inherit_gem` fails when gem is installed from git source

[jonrohan]

Description

When using inherit_gem in .erb-lint.yml to inherit configuration from a gem that's installed from a git source (rather than from RubyGems), erb_lint fails with a Gem::MissingSpecError.

Environment

• erb_lint version: 0.9.0
• Ruby version: 3.4.7
• Bundler: Using bundler standalone mode

Steps to Reproduce

1. Install a gem from git in your Gemfile:

gem "primer_view_components", github: "primer/view_components", ref: "5a6201b882e2fa8e46f1da466c3a85f21cfcbb2f"

2. Configure erb_lint to inherit from that gem in .erb-lint.yml:

inherit_gem:
  primer_view_components:
    - lib/primer/view_components/linters/accessibility.yml

3. Run erb_lint:

bundle exec erb_lint app/views/some_file.html.erb

Expected Behavior

erb_lint should successfully load the inherited configuration from the git-based gem.

Actual Behavior

Unable to find gem primer_view_components; is the gem installed? 
Could not find 'primer_view_components' (>= 0) among 672 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/path/to/vendor/gems/3.4.7/ruby/3.4.0'

Root Cause
In

erb_lint/lib/erb_lint/runner_config_resolver.rb

Line 53 in 52b6a4d

spec = Gem::Specification.find_by_name(gem_name)

, erb_lint uses Gem::Specification.find_by_name to locate gem paths:

def gem_config_path(gem, relative_config_path)
  gem_path = Gem::Specification.find_by_name(gem).gem_dir
  File.expand_path(relative_config_path, gem_path)
rescue Gem::LoadError
  raise Gem::LoadError, "Unable to find gem #{gem}; is the gem installed?"
end

However, Gem::Specification.find_by_name only works for gems installed from RubyGems. Git-sourced gems are installed to bundler/gems/ rather than gems/ and aren't discoverable via Gem::Specification.

Suggested Fix

Use Bundler's API to find gems, which works for both regular and git-sourced gems:

def gem_config_path(gem, relative_config_path)
  gem_path = if defined?(Bundler)
    spec = Bundler.load.specs.find { |s| s.name == gem }
    spec&.full_gem_path || Gem::Specification.find_by_name(gem).gem_dir
  else
    Gem::Specification.find_by_name(gem).gem_dir
  end
  
  File.expand_path(relative_config_path, gem_path)
rescue Gem::LoadError
  raise Gem::LoadError, "Unable to find gem #{gem}; is the gem installed?"
end