artist urls: normalize trailing slashes and missing http://.

* Remove unnecessary trailing slashes when artist URLs are saved.
* Automatically add `http://` to new artist URLs if it's missing (before
  this was an error; now it's automatically fixed).

app/models/artist_url.rb

@@ -72,8 +72,7 @@ class ArtistURL < ApplicationRecord
   end
 
   def domain
-    uri = Addressable::URI.parse(normalized_url)
-    uri.domain
+    Danbooru::URL.parse(normalized_url)&.domain
   end
 
   def site_name
@@ -119,11 +118,7 @@ class ArtistURL < ApplicationRecord
   end
 
   def self.normalize_url(url)
-    uri = Addressable::URI.parse(url)
-    uri.site = uri.normalized_site
-    uri.to_s
-  rescue Addressable::URI::InvalidURIError
-    url
+    Danbooru::URL.parse(url)&.to_s.presence || url
   end
 
   def url=(url)

test/unit/artist_test.rb

@@ -580,7 +580,8 @@ class ArtistTest < ActiveSupport::TestCase
 
       should "not save invalid urls" do
         assert_no_difference("ArtistVersion.count") do
-          @artist.update(:url_string => "http://foo.com www.example.com")
+          @artist.update(url_string: "http://foo.com :42")
+
           assert_equal(%w[http://foo.com], @artist.versions.last.urls)
         end
       end

test/unit/artist_url_test.rb

@@ -25,26 +25,29 @@ class ArtistURLTest < ActiveSupport::TestCase
 
     should "disallow invalid urls" do
       urls = [
-        FactoryBot.build(:artist_url, url: "www.example.com"),
-        FactoryBot.build(:artist_url, url: ":www.example.com"),
-        FactoryBot.build(:artist_url, url: "http://http://www.example.com"),
+        build(:artist_url, url: ":www.example.com"),
+        build(:artist_url, url: "http://http://www.example.com"),
       ]
 
       assert_equal(false, urls[0].valid?)
-      assert_match(/must begin with http/, urls[0].errors.full_messages.join)
+      assert_match(/is malformed/, urls[0].errors.full_messages.join)
       assert_equal(false, urls[1].valid?)
-      assert_match(/is malformed/, urls[1].errors.full_messages.join)
-      assert_equal(false, urls[2].valid?)
-      assert_match(/that does not contain a dot/, urls[2].errors.full_messages.join)
+      assert_match(/that does not contain a dot/, urls[1].errors.full_messages.join)
     end
 
-    should "always add a trailing slash when normalized" do
-      url = FactoryBot.create(:artist_url, :url => "http://monet.com")
+    should "automatically add http:// if missing" do
+      url = create(:artist_url, url: "example.com")
+      assert_equal("http://example.com", url.url)
+      assert_equal("http://example.com/", url.normalized_url)
+    end
+
+    should "normalize trailing slashes" do
+      url = create(:artist_url, url: "http://monet.com")
       assert_equal("http://monet.com", url.url)
       assert_equal("http://monet.com/", url.normalized_url)
 
-      url = FactoryBot.create(:artist_url, :url => "http://monet.com/")
-      assert_equal("http://monet.com/", url.url)
+      url = create(:artist_url, url: "http://monet.com/")
+      assert_equal("http://monet.com", url.url)
       assert_equal("http://monet.com/", url.normalized_url)
     end