artists: don't show unchanged URLs in artist history.

Only show changed URLs in the artist history, not unchanged URLs. Makes
the edit history more compact and easier to read by showing only the
things that changed on every edit.

app/helpers/application_helper.rb

@@ -5,9 +5,9 @@ module ApplicationHelper
     (fields.reduce(false) { |acc, field| acc || params.dig(:search, field).present? } && (!member_check || CurrentUser.is_member?) ? types[0] : types[1])
   end
 
-  def diff_list_html(this_list, other_list, ul_class: ["diff-list"], li_class: [])
+  def diff_list_html(this_list, other_list, ul_class: ["diff-list"], li_class: [], show_unchanged: true)
     diff = SetDiff.new(this_list, other_list)
-    render "diff_list", diff: diff, ul_class: ul_class, li_class: li_class
+    render "diff_list", diff: diff, ul_class: ul_class, li_class: li_class, show_unchanged: show_unchanged
   end
 
   def diff_name_html(this_name, other_name)

app/helpers/artist_versions_helper.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module ArtistVersionsHelper
-  def artist_version_other_names_diff(artist_version, type)
+  def artist_version_other_names_diff(artist_version, type, show_unchanged: false)
     other = artist_version.send(type)
     this_names = artist_version.other_names
     if other.present?
@@ -13,13 +13,13 @@ module ArtistVersionsHelper
     end
 
     if type == "previous"
-      diff_list_html(this_names, other_names)
+      diff_list_html(this_names, other_names, show_unchanged: show_unchanged)
     else
-      diff_list_html(other_names, this_names)
+      diff_list_html(other_names, this_names, show_unchanged: show_unchanged)
     end
   end
 
-  def artist_version_urls_diff(artist_version, type)
+  def artist_version_urls_diff(artist_version, type, show_unchanged: false)
     other = artist_version.send(type)
     this_urls = artist_version.urls
     if other.present?
@@ -31,9 +31,9 @@ module ArtistVersionsHelper
     end
 
     if type == "previous"
-      diff_list_html(this_urls, other_urls)
+      diff_list_html(this_urls, other_urls, show_unchanged: show_unchanged)
     else
-      diff_list_html(other_urls, this_urls)
+      diff_list_html(other_urls, this_urls, show_unchanged: show_unchanged)
     end
   end
 
@@ -53,7 +53,7 @@ module ArtistVersionsHelper
 
   def artist_version_group_name_diff(artist_version, type)
     other = artist_version.send(type)
-    if artist_version.group_name.present? || (other.present? && other.group_name.present?)
+    if artist_version.group_name.to_s != other&.group_name.to_s
       other_group_name = (other.present? ? other.group_name : artist_version.group_name)
       if type == "previous"
         group_name_diff = diff_name_html(artist_version.group_name, other_group_name)

app/views/application/_diff_list.html.erb

@@ -15,7 +15,9 @@
     <% end %>
   <% end %>
 
-  <% diff.unchanged.each do |item| %>
-    <%= tag.li item, class: ["unchanged", *li_class] %>
+  <% if show_unchanged %>
+    <% diff.unchanged.each do |item| %>
+      <%= tag.li item, class: ["unchanged", *li_class] %>
+    <% end %>
   <% end %>
 <% end %>