Avoid rendering an empty list in footer

We've had an accessibility error reported by the Spanish "Portal
Administración electrónica" (PAe). While I can't find any accessibility
rule saying empty lists should be avoided, it looks like some screen
readers report finding lists with 0 items, which is annoying.

We could also do it with CSS using `ul:empty { display: none}`. However,
at the time of writing no browser supports this rule when the tag
contains whitespace.

app/components/layout/social_component.rb

@@ -1,6 +1,10 @@
 class Layout::SocialComponent < ApplicationComponent
   delegate :content_block, to: :helpers
 
+  def render?
+    sites.any? || footer_content_block.present?
+  end
+
   private
 
     def sites
@@ -10,7 +14,7 @@ class Layout::SocialComponent < ApplicationComponent
         youtube: "https://www.youtube.com",
         telegram: "https://www.telegram.me",
         instragram: "https://www.instagram.com"
-      }.select { |name, _| setting["#{name}_handle"] }
+      }.select { |name, _| setting["#{name}_handle"].present? }
     end
 
     def link_title(site_name)

spec/components/layout/social_component_spec.rb

@@ -0,0 +1,39 @@
+require "rails_helper"
+
+describe Layout::SocialComponent, type: :component do
+  describe "#render?" do
+    it "renders when a social setting is present" do
+      Setting["twitter_handle"] = "myhandle"
+
+      render_inline Layout::SocialComponent.new
+
+      expect(page).to have_css "ul"
+    end
+
+    it "renders when a content block is present" do
+      Setting["twitter_handle"] = ""
+      Setting["facebook_handle"] = ""
+      Setting["youtube_handle"] = ""
+      Setting["telegram_handle"] = ""
+      Setting["instagram_handle"] = ""
+
+      create(:site_customization_content_block, name: "footer")
+
+      render_inline Layout::SocialComponent.new
+
+      expect(page).to have_css "ul"
+    end
+
+    it "does not render with no settings present and no content block present" do
+      Setting["twitter_handle"] = ""
+      Setting["facebook_handle"] = ""
+      Setting["youtube_handle"] = ""
+      Setting["telegram_handle"] = ""
+      Setting["instagram_handle"] = ""
+
+      render_inline Layout::SocialComponent.new
+
+      expect(page).not_to have_css "ul"
+    end
+  end
+end