ReactOnRails::Utils.bundle_js_file_path returns incorrect path for manifest.json

[elstgav]

I noticed that ReactOnRails::TestHelper.ensure_assets_compiled always reports that manifest.json is stale when running tests, even when the file exists and is up to date:

Detected the following stale generated files:
  manifest.json

After investigating, I believe this is because ReactOnRails::Utils.bundle_js_file_path() does not return the correct file path for 'manifest.json', so ReactOnRails::TestHelper.ensure_assets_compiled can’t accurately check if the file exists and is up to date.

Thanks to line 89 of lib/react_on_rails/utils.rb, it will always return 'manifest.json' instead of the correct path (e.g. '/path/to/rails/public/packs-test/manifest.json'):

def self.bundle_js_file_path(bundle_name)
  if using_webpacker?
    return bundle_name if bundle_name == "manifest.json"

So in summary:

Problem:

ReactOnRails::Utils.bundle_js_file_path('manifest.json')
returns 'manifest.json'

Expected:

ReactOnRails::Utils.bundle_js_file_path('manifest.json')
returns '/path/to/rails/public/packs-test/manifest.json'

Proposed Solution:

Change ReactOnRails::Utils.bundle_js_file_path to

def self.bundle_js_file_path(bundle_name)
  if using_webpacker? && bundle_name != "manifest.json"
    bundle_js_file_path_from_webpacker(bundle_name)
  else
    # Default to the non-hashed name in the specified output directory, which, for legacy
    # React on Rails, this is the output directory picked up by the asset pipeline.
    File.join(ReactOnRails.configuration.generated_assets_dir, bundle_name)
  end
end

[justin808]

@elstgav good work. Please submit a PR.