Add support for using view components in rails engine

[tkowalewski]

What are you trying to accomplish?

I'm trying to add support for generating view components in the module (engine) namespace in rails engine.
To do it we need to wrap templates code with module_namespacing (provided by rails)

How to test

1. Create new rails engine

rails plugin new engine_with_test --mountable

2. Update gemspec (engine_with_test.gemspec)
   Update spec.homepage
   Update spec.summary
   Update spec.description
   Update spec.metadata["source_code_uri"]
   Update spec.metadata["changelog_uri"]

3. Add view_component to Gemfile

gem "view_component", github: "tkowalewski/view_component", branch: "component_template_with_module_namespacing"

4. Install gems

bundle install

5. Generate example component

bin/rails generate component Example message --preview

6. Update component template (app/components/engine_with_test/example_component.html.erb)

<span><%= @message %></span>

7. Uncomment test (test/components/engine_with_test/example_component_test.rb)

8. Run tests

bin/rails test

9. Preview component

bin/rails server

and go to http://localhost:3000/rails/view_components

What approach did you choose and why?

There is only one solution to deliver view components for rails engine with module (engine) namespace: Wrap templates code with module_namespacing :)

Anything you want to highlight for special attention from reviewers?

• I had to prepare dummy rails engine for tests (test/dummy)
• New rake test task (engine_test) was added to Rakefile
• ViewComponent configuration has been extended to provide preview paths for rails engine

[boardfish]

👋 Just a quick nudge to say #1308 means you'll need to rebase this branch for checks to pass.

[tkowalewski]

@boardfish @Spone

There is problem with tests for main release of rails :|
Any plans to add support for rails 8.0.0.alpha?