ah, forgot about mocked channel

test/Discord.Net.Tests.Unit/MockedEntities/MockedTextChannel.cs

@@ -214,11 +214,12 @@ namespace Discord
         {
             throw new NotImplementedException();
         }
-
+        
         public Task<IUserMessage> SendFileAsync(FileAttachment attachment, string text = null, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null, MessageFlags flags = MessageFlags.None) => throw new NotImplementedException();
         public Task<IUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text = null, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null, MessageFlags flags = MessageFlags.None) => throw new NotImplementedException();
         public Task<IThreadChannel> CreateThreadAsync(string name, ThreadType type = ThreadType.PublicThread, ThreadArchiveDuration autoArchiveDuration = ThreadArchiveDuration.OneDay, IMessage message = null, bool? invitable = null, int? slowmode = null, RequestOptions options = null, MessageFlags flags = MessageFlags.None) => throw new NotImplementedException();
         public Task<IInviteMetadata> CreateInviteToApplicationAsync(DefaultApplications application, int? maxAge = 86400, int? maxUses = null, bool isTemporary = false, bool isUnique = false, RequestOptions options = null) => throw new NotImplementedException();
         public Task<IThreadChannel> CreateThreadAsync(string name, ThreadType type = ThreadType.PublicThread, ThreadArchiveDuration autoArchiveDuration = ThreadArchiveDuration.OneDay, IMessage message = null, bool? invitable = null, int? slowmode = null, RequestOptions options = null) => throw new NotImplementedException();
+        public Task<IReadOnlyCollection<IThreadChannel>> GetActiveThreadsAsync(RequestOptions options = null) => throw new NotImplementedException();
     }
 }