Fix #3738: Artist URL search should be case-insensitive for domains.

app/models/artist_url.rb

@@ -19,6 +19,7 @@ class ArtistUrl < ApplicationRecord
       nil
     else
       url = url.sub(%r!^https://!, "http://")
+      url = url.sub(%r!^http://([^/]+)!i) { |domain| domain.downcase }
       url = url.sub(%r!^http://blog\d+\.fc2!, "http://blog.fc2")
       url = url.sub(%r!^http://blog-imgs-\d+\.fc2!, "http://blog.fc2")
       url = url.sub(%r!^http://blog-imgs-\d+-\w+\.fc2!, "http://blog.fc2")

test/unit/artist_test.rb

@@ -205,6 +205,11 @@ class ArtistTest < ActiveSupport::TestCase
       assert_equal(["minko"], Artist.find_all_by_url("http://minko.com/x/test.jpg").map(&:name))
     end
 
+    should "be case-insensitive to domains when finding matches by url" do
+      a1 = FactoryBot.create(:artist, name: "bkub", url_string: "http://BKUB.example.com")
+      assert_artist_found(a1.name, "http://bkub.example.com")
+    end
+
     should "not find duplicates" do
       FactoryBot.create(:artist, :name => "warhol", :url_string => "http://warhol.com/x/a/image.jpg\nhttp://warhol.com/x/b/image.jpg")
       assert_equal(["warhol"], Artist.find_all_by_url("http://warhol.com/x/test.jpg").map(&:name))

test/unit/artist_url_test.rb

@@ -35,6 +35,11 @@ class ArtistUrlTest < ActiveSupport::TestCase
       assert_equal("http://google.com/", url.normalized_url)
     end
 
+    should "normalise domains to lowercase" do
+      url = FactoryBot.create(:artist_url, url: "https://ArtistName.example.com")
+      assert_equal("http://artistname.example.com/", url.normalized_url)
+    end
+
     context "normalize twitter profile urls" do
       setup do
         @url = FactoryBot.create(:artist_url, :url => "https://twitter.com/BLAH")