tests: fix broken tests.

app/logical/sources/strategies/nico_seiga.rb

@@ -40,7 +40,7 @@ module Sources
       end
 
       def profile_url
-        "https://seiga.nicovideo.jp/user/illust/#{api_client.user_id}" if api_client.user_id.present?
+        "https://seiga.nicovideo.jp/user/illust/#{api_client.user_id}" if api_client&.user_id.present?
       end
 
       def artist_name

app/logical/sources/strategies/null.rb

@@ -15,6 +15,10 @@ module Sources
         url
       end
 
+      def artists
+        ArtistFinder.find_artists(url)
+      end
+
       def normalize_for_source
         case url
         when %r{\Ahttp://www\.karabako\.net/images(?:ub)?/karabako_(\d+)(?:_\d+)?\.}i

app/logical/sources/strategies/twitter.rb

@@ -30,7 +30,7 @@ module Sources::Strategies
     def image_urls
       # https://pbs.twimg.com/media/EBGbJe_U8AA4Ekb.jpg:orig
       if parsed_url.image_url?
-        [parsed_url.orig_image_url]
+        [parsed_url.full_image_url]
       elsif api_response.present?
         api_response.dig(:extended_entities, :media).to_a.map do |media|
           if media[:type] == "photo"
@@ -43,7 +43,7 @@ module Sources::Strategies
           end
         end
       else
-        [url]
+        []
       end
     end