Use system specs instead of feature specs

We get rid of database cleaner, and JavaScript tests are faster because
between tests we now rollback transactions instead of truncating the
database.

spec/shared/system/followable.rb

@@ -0,0 +1,103 @@
+shared_examples "followable" do |followable_class_name, followable_path, followable_path_arguments|
+  let!(:arguments) { {} }
+  let!(:followable) { create(followable_class_name) }
+  let!(:followable_dom_name) { followable_class_name.tr("_", "-") }
+
+  def dom_id(record)
+    ActionView::RecordIdentifier.dom_id(record)
+  end
+
+  before do
+    followable_path_arguments.each do |argument_name, path_to_value|
+      arguments.merge!("#{argument_name}": followable.send(path_to_value))
+    end
+  end
+
+  context "Show" do
+    scenario "Should not display follow button when there is no logged user" do
+      visit send(followable_path, arguments)
+
+      within "##{dom_id(followable)}" do
+        expect(page).not_to have_link("Follow")
+      end
+    end
+
+    scenario "Should display follow button when user is logged in" do
+      user = create(:user)
+      login_as(user)
+
+      visit send(followable_path, arguments)
+
+      within "##{dom_id(followable)}" do
+        expect(page).to have_link("Follow #{followable.model_name.human.downcase}")
+      end
+    end
+
+    scenario "Should display follow button when user is logged and is not following" do
+      user = create(:user)
+      login_as(user)
+
+      visit send(followable_path, arguments)
+      expect(page).to have_link("Follow #{followable.model_name.human.downcase}")
+    end
+
+    scenario "Should display unfollow after user clicks on follow button", :js do
+      user = create(:user)
+      login_as(user)
+
+      visit send(followable_path, arguments)
+      within "##{dom_id(followable)}" do
+        click_link("Follow #{followable.model_name.human.downcase}")
+
+        expect(page).not_to have_link("Follow")
+        expect(page).to have_link("Following")
+      end
+    end
+
+    scenario "Should display new follower notice after user clicks on follow button", :js do
+      user = create(:user)
+      login_as(user)
+
+      visit send(followable_path, arguments)
+      within "##{dom_id(followable)}" do
+        click_link("Follow #{followable.model_name.human.downcase}")
+      end
+
+      expect(page).to have_content "We will notify you of changes as they occur"
+    end
+
+    scenario "Display unfollow button when user already following" do
+      user = create(:user, followables: [followable])
+      login_as(user)
+
+      visit send(followable_path, arguments)
+
+      expect(page).to have_link("Following")
+    end
+
+    scenario "Updates follow button & show destroy notice after unfollow button is clicked", :js do
+      user = create(:user, followables: [followable])
+      login_as(user)
+
+      visit send(followable_path, arguments)
+      within "##{dom_id(followable)}" do
+        click_link("Unfollow #{followable.model_name.human.downcase}")
+
+        expect(page).not_to have_link("Unfollow")
+        expect(page).to have_link("Follow #{followable.model_name.human.downcase}")
+      end
+    end
+
+    scenario "Should display destroy follower notice after user clicks on unfollow button", :js do
+      user = create(:user, followables: [followable])
+      login_as(user)
+
+      visit send(followable_path, arguments)
+      within "##{dom_id(followable)}" do
+        click_link("Unfollow #{followable.model_name.human.downcase}")
+      end
+
+      expect(page).to have_content "You will no longer receive notifications"
+    end
+  end
+end