precompile_hook detection always returns false due to regex mismatch

[ihabadham]

Environment

1. Ruby version: 3.3.7
2. Rails version: 8.0.4
3. Shakapacker version: 9.4.0
4. React on Rails version: 16.2.0.rc.0

Summary

The shakapacker_precompile_hook_configured? detection method always returns false even when precompile_hook is properly configured, because the regex looks for react_on_rails:generate_packs but the generator template uses generate_packs_if_stale.

Expected behavior

When precompile_hook: 'bin/shakapacker-precompile-hook' is configured in shakapacker.yml, the detection should return true:

ReactOnRails::PackerUtils.shakapacker_precompile_hook_configured?
# => true

Actual behavior

Detection always returns false:

ReactOnRails::PackerUtils.shakapacker_precompile_hook_configured?
# => false

Root Cause

In packer_utils.rb:204-219, the detection checks if the hook script contains the string react_on_rails:generate_packs:

def self.hook_contains_generate_packs?(hook_value)
  # ...
  return true if hook_value.to_s.match?(/\breact_on_rails:generate_packs\b/)
  # ...
  script_contents = File.read(script_path)
  script_contents.match?(/\breact_on_rails:generate_packs\b/)
end

But the generator template (templates/base/base/bin/shakapacker-precompile-hook) uses:

ReactOnRails::PacksGenerator.instance.generate_packs_if_stale

These strings don't match, so detection fails.

Steps to Reproduce

# After running generator with precompile_hook properly configured:
rails runner "
  puts 'Hook value: ' + ReactOnRails::PackerUtils.shakapacker_precompile_hook_value.inspect
  puts 'Detection: ' + ReactOnRails::PackerUtils.shakapacker_precompile_hook_configured?.to_s
  
  content = File.read('bin/shakapacker-precompile-hook')
  puts 'Contains react_on_rails:generate_packs: ' + content.include?('react_on_rails:generate_packs').to_s
  puts 'Contains generate_packs_if_stale: ' + content.include?('generate_packs_if_stale').to_s
"
# Output:
# Hook value: "bin/shakapacker-precompile-hook"
# Detection: false
# Contains react_on_rails:generate_packs: false
# Contains generate_packs_if_stale: true

Impact

Low severity for standard Shakapacker flow because:

• The detection is only used in bin/dev (to skip redundant generation) and adjust_precompile_task
• adjust_precompile_task returns early for standard flow (build_production_command.blank?)
• bin/dev just does redundant (but harmless) pack generation

Higher severity for custom build_production_command scenarios:

• Detection fails → fallback runs generate_packs rake task
• But hook also runs → potential double pack generation

Suggested Fix

Update the regex to also match generate_packs_if_stale:

def self.hook_contains_generate_packs?(hook_value)
  return false if hook_value.blank?
  
  pattern = /\b(react_on_rails:generate_packs|generate_packs_if_stale)\b/
  
  return true if hook_value.to_s.match?(pattern)
  
  script_path = resolve_hook_script_path(hook_value)
  return false unless script_path && File.exist?(script_path)
  
  script_contents = File.read(script_path)
  script_contents.match?(pattern)
rescue StandardError
  false
end

Related

• Generator doesn't configure precompile_hook in shakapacker.yml when Shakapacker is pre-installed #2278 (precompile_hook not configured in generator)
• PR Add Shakapacker precompile hook template for generator #1916 (added precompile_hook feature)