Refactor ArticleHelper#get_host_without_www (#4558) [ci skip]

Also add specs for it

app/helpers/articles_helper.rb

@@ -49,7 +49,7 @@ module ArticlesHelper
   def get_host_without_www(url)
     url = "http://#{url}" if URI.parse(url).scheme.nil?
     host = URI.parse(url).host.downcase
-    host.gsub!("medium.com", "Medium") if host.include?("medium.com")
-    host.start_with?("www.") ? host[4..-1] : host
+    host.gsub!("medium.com", "Medium")
+    host.delete_prefix("www.")
   end
 end

spec/helpers/articles_helper_spec.rb

@@ -0,0 +1,25 @@
+require "rails_helper"
+
+describe ArticlesHelper do
+  describe ".get_host_without_www" do
+    it "drops the www off of a valid url" do
+      host = helper.get_host_without_www("https://www.example.com")
+      expect(host).to eq "example.com"
+    end
+
+    it "lowercases the host name in general" do
+      host = helper.get_host_without_www("https://www.EXAMPLE.COM")
+      expect(host).to eq "example.com"
+    end
+
+    it "titlecases the host for medium.com and drops .com" do
+      host = helper.get_host_without_www("https://www.medium.com")
+      expect(host).to eq "Medium"
+    end
+
+    it "can handle urls without schemes" do
+      host = helper.get_host_without_www("www.example.com")
+      expect(host).to eq "example.com"
+    end
+  end
+end