error_unless_package_manager_is_obvious! triggers when rails environment is required from outside the rails root

[marvinthepa]

Expected behavior:

When running rails code from outside the rails root, it should still work.

Actual behavior:

It errors because of the package json check:

vendor/bundle/ruby/3.3/gems/package_json-0.1.0/lib/package_json.rb:25:in `read': $DIR does not contain a package.json (PackageJson::Error)
from vendor/bundle/ruby/3.3/gems/shakapacker-8.0.2/lib/shakapacker/utils/manager.rb:19:in `error_unless_package_manager_is_obvious!'
from vendor/bundle/ruby/3.3/gems/shakapacker-8.0.2/lib/shakapacker/railtie.rb:20:in `block in <class:Engine>'
from vendor/bundle/ruby/3.3/gems/railties-7.1.3.4/lib/rails/initializable.rb:32:in `instance_exec'
from vendor/bundle/ruby/3.3/gems/railties-7.1.3.4/lib/rails/initializable.rb:32:in `run'
from vendor/bundle/ruby/3.3/gems/railties-7.1.3.4/lib/rails/initializable.rb:61:in `block in run_initializers'
from /usr/local/lib/ruby/3.3/tsort.rb:231:in `block in tsort_each'
from /usr/local/lib/ruby/3.3/tsort.rb:353:in `block (2 levels) in each_strongly_connected_component'
from /usr/local/lib/ruby/3.3/tsort.rb:434:in `each_strongly_connected_component_from'
from /usr/local/lib/ruby/3.3/tsort.rb:352:in `block in each_strongly_connected_component'
from /usr/local/lib/ruby/3.3/tsort.rb:350:in `each'
from /usr/local/lib/ruby/3.3/tsort.rb:350:in `call'
from /usr/local/lib/ruby/3.3/tsort.rb:350:in `each_strongly_connected_component'
from /usr/local/lib/ruby/3.3/tsort.rb:229:in `tsort_each'
from /usr/local/lib/ruby/3.3/tsort.rb:208:in `tsort_each'
from vendor/bundle/ruby/3.3/gems/railties-7.1.3.4/lib/rails/initializable.rb:60:in `run_initializers'
from vendor/bundle/ruby/3.3/gems/railties-7.1.3.4/lib/rails/application.rb:426:in `initialize!'
from config/environment.rb:12:in `<top (required)>'
from <internal:/usr/local/lib/ruby/3.3/rubygems/core_ext/kernel_require.rb>:136:in `require'
from <internal:/usr/local/lib/ruby/3.3/rubygems/core_ext/kernel_require.rb>:136:in `require'
from test/test_helper.rb:25:in `<top (required)>'

test_helper.rb:25 contains

require File.expand_path('../config/environment', __dir__)

Small, reproducible repo:

Should be easy to set up, just init a rails repo, lets say in "reproducer", then add a ruby file one level up with the following content:

require File.expand_path('reproducer/config/environment', __dir__)

Setup environment:

• Ruby version: 3.3.2
• Rails version: 7.1.3.4
• Shakapacker version: 8.0.2

I think the issue is in

      def self.error_unless_package_manager_is_obvious!
        return unless PackageJson.read.fetch("packageManager", nil).nil?

This should be something along the lines of

      def self.error_unless_package_manager_is_obvious!
        return unless PackageJson.read(Rails.root).fetch("packageManager", nil).nil?

(at least this fixes it for me - of course you might not what the dependency to rails here, but rather in the railtie..).

Btw. self.guess_binary seems to have the same issue, it looks for the lockfile in the current directory instead of the rails root.
On the other hand, Shakapacker::VersionChecker::NodePackageVersion.package_json_path finds the correct package.json, so maybe error_unless_package_manager_is_obvious should use that instead?