FIX: Site's top tags not shown for anonymous user (#22219)

When a site does not have `default_navigation_menu_tags`
site setting set, anonymous users should be shown the site's top tags as
a default in the tags section. However, this regressed in 9fad71809c
and we ended up showing anonymous users a tags section with only the
`All Tags` section link.

As part of this commit, I have also refactored the QUnit acceptance
tests to system tests which are much easier to work with.

spec/system/page_objects/components/sidebar.rb

@@ -83,6 +83,27 @@ module PageObjects
         has_section?("Tags")
       end
 
+      def has_no_tags_section?
+        has_no_section?("Tags")
+      end
+
+      def has_all_tags_section_link?
+        has_section_link?(I18n.t("js.sidebar.all_tags"))
+      end
+
+      def has_tags_section_links?(tags)
+        section_selector = ".sidebar-section[data-section-name='tags']"
+        tag_names = tags.map(&:name)
+
+        has_css?(
+          "#{section_selector} .sidebar-section-link-wrapper[data-tag-name]",
+          count: tag_names.length,
+        ) &&
+          all("#{section_selector} .sidebar-section-link-wrapper[data-tag-name]").all? do |row|
+            tag_names.include?(row["data-tag-name"].to_s)
+          end
+      end
+
       def has_no_section?(name)
         find(SIDEBAR_WRAPPER_SELECTOR).has_no_button?(name)
       end

spec/system/viewing_sidebar_as_anonymous_user_spec.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+describe "Viewing sidebar as anonymous user", type: :system do
+  fab!(:tag1) { Fabricate(:tag).tap { |tag| Fabricate.times(1, :topic, tags: [tag]) } }
+  fab!(:tag2) { Fabricate(:tag).tap { |tag| Fabricate.times(2, :topic, tags: [tag]) } }
+  fab!(:tag3) { Fabricate(:tag).tap { |tag| Fabricate.times(3, :topic, tags: [tag]) } }
+  fab!(:tag4) { Fabricate(:tag).tap { |tag| Fabricate.times(2, :topic, tags: [tag]) } }
+  fab!(:tag5) { Fabricate(:tag).tap { |tag| Fabricate.times(2, :topic, tags: [tag]) } }
+  fab!(:tag6) { Fabricate(:tag).tap { |tag| Fabricate.times(1, :topic, tags: [tag]) } }
+
+  let(:sidebar) { PageObjects::Components::Sidebar.new }
+
+  describe "when viewing the tags section" do
+    it "should not display the tags section when tagging has been disabled" do
+      SiteSetting.tagging_enabled = false
+
+      visit("/latest")
+
+      expect(sidebar).to have_no_tags_section
+    end
+
+    it "should not display the tags section when site has no top tags and `default_navigation_menu_tags` site setting has not been set" do
+      Tag.delete_all
+
+      visit("/latest")
+
+      expect(sidebar).to have_no_tags_section
+    end
+
+    it "should display the site's top tags when `default_navigation_menu_tags` site setting has not been set" do
+      visit("/latest")
+
+      expect(sidebar).to have_tags_section
+      expect(sidebar).to have_all_tags_section_link
+      expect(sidebar).to have_tags_section_links([tag1, tag2, tag3, tag4, tag5])
+    end
+
+    it "should display the site's top tags when `default_navigation_menu_tags` site setting has been set but the tags configured are hidden to the user" do
+      SiteSetting.default_navigation_menu_tags = "#{tag5.name}"
+      Fabricate(:tag_group, permissions: { "staff" => 1 }, tag_names: [tag5.name])
+
+      visit("/latest")
+
+      expect(sidebar).to have_tags_section
+      expect(sidebar).to have_all_tags_section_link
+      expect(sidebar).to have_tags_section_links([tag1, tag2, tag3, tag4, tag6])
+    end
+
+    it "should display the tags configured in `default_navigation_menu_tags` site setting when it has been set" do
+      SiteSetting.default_navigation_menu_tags = "#{tag3.name}|#{tag4.name}"
+
+      visit("/latest")
+
+      expect(sidebar).to have_tags_section
+      expect(sidebar).to have_all_tags_section_link
+      expect(sidebar).to have_tags_section_links([tag3, tag4])
+    end
+  end
+end