Action Text installer should assume importmap for asset pipeline (rails#43011)

* Action Text installer should assume importmap for asset pipeline

* Fix test

Author: David Heinemeier Hansson

actiontext/lib/generators/action_text/install/install_generator.rb

@@ -44,13 +44,11 @@ def append_javascript_dependencies
             end
           end
         else
-          if (application_layout_path = Rails.root.join("app/views/layouts/application.html.erb")).exist?
-            insert_into_file application_layout_path.to_s, %(\n    <%= javascript_include_tag "trix", "actiontext", "data-turbo-track": "reload", defer: true %>), before: /\s*<\/head>/
+          if (application_javascript_path = Rails.root.join("app/assets/javascripts/application.js")).exist?
+            insert_into_file application_javascript_path.to_s, %(\nimport "trix"\nimport "@rails/actiontext")
           else
             say <<~INSTRUCTIONS, :green
-              You must add the actiontext.js and trix.js JavaScript files to the head of your application layout:
-
-              <%= javascript_include_tag "trix", "actiontext", "data-turbo-track": "reload", defer: true %>
+              You must import the @rails/actiontext.js and trix.js JavaScript files in your application entrypoint.
             INSTRUCTIONS
           end
         end

railties/test/generators/action_text_install_generator_test.rb

@@ -103,13 +103,13 @@ class ActionText::Generators::InstallGeneratorTest < Rails::Generators::TestCase
   test "run just for asset pipeline" do
     run_under_asset_pipeline
 
-    application_layout = Pathname("app/views/layouts/application.html.erb").expand_path(destination_root)
-    application_layout.dirname.mkpath
-    application_layout.write("</head>\n")
+    application_js = Pathname("app/assets/javascripts/application.js").expand_path(destination_root)
+    application_js.dirname.mkpath
+    application_js.write ""
 
     run_generator_instance
 
-    assert_file application_layout do |content|
+    assert_file application_js do |content|
       assert_match %r"trix", content
     end
   end