There is only one component now, platform inside the
components/platform folder.
This component is just a Rails engine. With just a model User defined inside
components/platform/app/models/user.rb.
You can run platform tests using bin/rails test components/platforms. Those tests using the application's
test helper.
This component was genereted with bin/rails plugin new components/platform --mountable but removing a few files:
Gemfile. The component uses the application's Gemfile, since it is part of the application, not a standalone thing.test_helper. The component uses the application's test helper.bin.
Those deletion are being made separately.
The application app folder only have the assets, everything else is in the components.