test connection by trying to get 1 result from each provided playlist

src/NzbDrone.Core/ImportLists/Youtube/YoutubeImportListBase.cs

@@ -57,9 +57,17 @@ namespace NzbDrone.Core.ImportLists.Youtube
             failures.AddIfNotNull(TestConnection());
         }
 
+        public abstract ValidationFailure TestConnection(YouTubeService service);
+
         private ValidationFailure TestConnection()
         {
-            return null;
+            using (var service = new YouTubeService(new BaseClientService.Initializer()
+                   {
+                       ApiKey = Settings.YoutubeApiKey,
+                   }))
+            {
+             return   TestConnection(service);
+            }
         }
     }
 }

src/NzbDrone.Core/ImportLists/Youtube/YoutubePlaylist.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using DryIoc.ImTools;
+using FluentValidation.Results;
 using Google.Apis.YouTube.v3;
 using Google.Apis.YouTube.v3.Data;
 using NLog;
@@ -94,5 +95,25 @@ namespace NzbDrone.Core.ImportLists.Youtube
         {
             return (playlistItem.ContentDetails.VideoPublishedAtDateTimeOffset ?? DateTimeOffset.UnixEpoch).DateTime;
         }
+
+        public override ValidationFailure TestConnection(YouTubeService service)
+        {
+            foreach (var id in Settings.PlaylistIds)
+            {
+                try
+                {
+                    var req = service.PlaylistItems.List("contentDetails,snippet");
+                    req.PlaylistId = id;
+                    req.MaxResults = 1;
+                    req.Execute();
+                }
+                catch (Exception e)
+                {
+                    return new ValidationFailure(string.Empty, e.Message);
+                }
+            }
+
+            return null;
+        }
     }
 }