Use Zeitwerk instead of the classic autoloader

In Rails 6.1, the classic autoloader is deprecated.

We were getting an error because we were using `autoload` in the
ActiveStorage plugin for CKEditor:

expected file app/lib/ckeditor/backend/active_storage.rb to define
constant Ckeditor::Backend::ActiveStorage

So we're removing the line causing the error.

Finally, we can now restore all the tests that that failed sometimes
with the classic autoloader and that we modified in commits 2af1fc72f
and 8ba37b295.

app/lib/ckeditor/backend/active_storage.rb

@@ -67,7 +67,5 @@ module Ckeditor
           end
       end
     end
-
-    autoload :ActiveStorage, "ckeditor/backend/active_storage"
   end
 end

config/application.rb

@@ -32,10 +32,6 @@ module Consul
     # in any CONSUL DEMOCRACY installations
     config.active_support.use_authenticated_message_encryption = false
 
-    # Keep using the classic autoloader until we decide how custom classes
-    # should work with zeitwerk
-    config.autoloader = :classic
-
     # Don't enable has_many_inversing because it doesn't seem to currently
     # work with the _count database columns we use for caching purposes
     config.active_record.has_many_inversing = false
@@ -143,6 +139,7 @@ module Consul
       "app/models/custom/concerns"
     ].each do |path|
       config.autoload_paths << Rails.root.join(path)
+      config.eager_load_paths << Rails.root.join(path)
     end
 
     config.paths["app/views"].unshift(Rails.root.join("app", "views", "custom"))

config/environments/development.rb

@@ -72,6 +72,7 @@ Rails.application.configure do
   # Annotate rendered view with file names.
   # config.action_view.annotate_rendered_view_with_filenames = true
 
+  config.eager_load_paths << "#{Rails.root}/spec/mailers/previews"
   config.action_mailer.preview_path = "#{Rails.root}/spec/mailers/previews"
 
   # Limit size of local logs

spec/system/admin/homepage/homepage_spec.rb

@@ -178,16 +178,15 @@ describe "Homepage", :admin do
                                  link_text: "Link1 text",
                                  link_url: "consul1.dev")
 
-    # TODO: uncomment again after switching to zeitwerk
+    card2 = create(:widget_card, label: "Card2 label",
-    # card2 = create(:widget_card, label: "Card2 label",
+                                 title: "Card2 text",
-    #                              title: "Card2 text",
+                                 description: "Card2 description",
-    #                              description: "Card2 description",
+                                 link_text: "Link2 text",
-    #                              link_text: "Link2 text",
+                                 link_url: "consul2.dev")
-    #                              link_url: "consul2.dev")
 
     visit root_path
 
-    expect(page).to have_css(".card", count: 1) # TODO: change to `count: 2 after switching to zeitwerk
+    expect(page).to have_css(".card", count: 2)
 
     within("#widget_card_#{card1.id}") do
       expect(page).to have_content("CARD1 LABEL")
@@ -198,15 +197,14 @@ describe "Homepage", :admin do
       expect(page).to have_css("img[alt='#{card1.image.title}']")
     end
 
-    # TODO: uncomment again after switching to zeitwerk
+    within("#widget_card_#{card2.id}") do
-    # within("#widget_card_#{card2.id}") do
+      expect(page).to have_content("CARD2 LABEL")
-    #   expect(page).to have_content("CARD2 LABEL")
+      expect(page).to have_content("CARD2 TEXT")
-    #   expect(page).to have_content("CARD2 TEXT")
+      expect(page).to have_content("Card2 description")
-    #   expect(page).to have_content("Card2 description")
+      expect(page).to have_content("Link2 text")
-    #   expect(page).to have_content("Link2 text")
+      expect(page).to have_link(href: "consul2.dev")
-    #   expect(page).to have_link(href: "consul2.dev")
+      expect(page).to have_css("img[alt='#{card2.image.title}']")
-    #   expect(page).to have_css("img[alt='#{card2.image.title}']")
+    end
-    # end
   end
 
   scenario "Recomendations" do

spec/system/admin/widgets/cards_spec.rb

@@ -59,16 +59,14 @@ describe "Cards", :admin do
 
   scenario "Show" do
     card_1 = create(:widget_card, title: "Card homepage large", columns: 8)
-    # TODO: uncomment after switching to zeitwerk
+    card_2 = create(:widget_card, title: "Card homepage medium", columns: 4)
-    # card_2 = create(:widget_card, title: "Card homepage medium", columns: 4)
+    card_3 = create(:widget_card, title: "Card homepage small", columns: 2)
-    # card_3 = create(:widget_card, title: "Card homepage small", columns: 2)
 
     visit root_path
 
     expect(page).to have_css("#widget_card_#{card_1.id}.medium-8")
-    # TODO: uncomment after switching to zeitwerk
+    expect(page).to have_css("#widget_card_#{card_2.id}.medium-4")
-    # expect(page).to have_css("#widget_card_#{card_2.id}.medium-4")
+    expect(page).to have_css("#widget_card_#{card_3.id}.medium-2")
-    # expect(page).to have_css("#widget_card_#{card_3.id}.medium-2")
   end
 
   scenario "Edit" do

spec/system/polls/polls_spec.rb

@@ -26,7 +26,7 @@ describe "Polls" do
     end
 
     scenario "Polls can be listed" do
-      polls = [create(:poll, :with_image)] # TODO: generate a list again after switching to zeitwerk
+      polls = create_list(:poll, 3, :with_image)
 
       visit polls_path
 
@@ -210,24 +210,23 @@ describe "Polls" do
       expect("Second question").to appear_before("Third question")
     end
 
-    # TODO: uncomment after switching to zeitwerk
+    scenario "Buttons to slide through images work back and forth" do
-    # scenario "Buttons to slide through images work back and forth" do
+      question = create(:poll_question, :yes_no, poll: poll)
-    #   question = create(:poll_question, :yes_no, poll: poll)
+      create(:image, imageable: question.question_answers.last, title: "The no movement")
-    #   create(:image, imageable: question.question_answers.last, title: "The no movement")
+      create(:image, imageable: question.question_answers.last, title: "No movement planning")
-    #   create(:image, imageable: question.question_answers.last, title: "No movement planning")
 
-    #   visit poll_path(poll)
+      visit poll_path(poll)
 
-    #   within(".orbit-bullets") do
+      within(".orbit-bullets") do
-    #     find("[data-slide='1']").click
+        find("[data-slide='1']").click
 
-    #     expect(page).to have_css ".is-active[data-slide='1']"
+        expect(page).to have_css ".is-active[data-slide='1']"
 
-    #     find("[data-slide='0']").click
+        find("[data-slide='0']").click
 
-    #     expect(page).to have_css ".is-active[data-slide='0']"
+        expect(page).to have_css ".is-active[data-slide='0']"
-    #   end
+      end
-    # end
+    end
 
     scenario "Non-logged in users" do
       create(:poll_question, :yes_no, poll: poll)