Multi file upload + attachment editing

src/Discord.Net.Core/Entities/Channels/IMessageChannel.cs

@@ -129,7 +129,6 @@ namespace Discord
         /// <param name="isTTS">Whether the message should be read aloud by Discord or not.</param>
         /// <param name="embed">The <see cref="Discord.EmbedType.Rich"/> <see cref="Embed"/> to be sent.</param>
         /// <param name="options">The options to be used when sending the request.</param>
-        /// <param name="isSpoiler">Whether the message attachment should be hidden as a spoiler.</param>
         /// <param name="allowedMentions">
         ///     Specifies if notifications are sent for mentioned users and roles in the message <paramref name="text"/>.
         ///     If <c>null</c>, all mentioned roles and users will be notified.
@@ -142,7 +141,7 @@ namespace Discord
         ///     A task that represents an asynchronous send operation for delivering the message. The task result
         ///     contains the sent message.
         /// </returns>
-        Task<IUserMessage> SendFileAsync(FileAttachment attachment, string text = null, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null);
+        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);
         /// <summary>
         ///     Sends a collection of files to this message channel.
         /// </summary>
@@ -159,7 +158,6 @@ namespace Discord
         /// <param name="isTTS">Whether the message should be read aloud by Discord or not.</param>
         /// <param name="embed">The <see cref="Discord.EmbedType.Rich"/> <see cref="Embed"/> to be sent.</param>
         /// <param name="options">The options to be used when sending the request.</param>
-        /// <param name="isSpoiler">Whether the message attachment should be hidden as a spoiler.</param>
         /// <param name="allowedMentions">
         ///     Specifies if notifications are sent for mentioned users and roles in the message <paramref name="text"/>.
         ///     If <c>null</c>, all mentioned roles and users will be notified.
@@ -172,7 +170,7 @@ namespace Discord
         ///     A task that represents an asynchronous send operation for delivering the message. The task result
         ///     contains the sent message.
         /// </returns>
-        Task<IUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text = null, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null);
+        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);
 
         /// <summary>
         ///     Gets a message from this message channel.

src/Discord.Net.Core/Entities/Messages/FileAttachment.cs

@@ -11,6 +11,7 @@ namespace Discord
     {
         public string FileName { get; set; }
         public string Description { get; set; }
+        public bool IsSpoiler { get; set; }
 
 #pragma warning disable IDISP008
         public Stream Stream { get; }
@@ -24,12 +25,13 @@ namespace Discord
         /// <param name="stream">The stream to create the attachment from.</param>
         /// <param name="fileName">The name of the attachment.</param>
         /// <param name="description">The description of the attachment.</param>
-        public FileAttachment(Stream stream, string fileName, string description = null)
+        public FileAttachment(Stream stream, string fileName, string description = null, bool isSpoiler = false)
         {
             _isDisposed = false;
             FileName = fileName;
             Description = description;
             Stream = stream;
+            IsSpoiler = isSpoiler;
         }
 
         /// <summary>
@@ -60,12 +62,13 @@ namespace Discord
         /// <exception cref="FileNotFoundException">The file specified in <paramref name="path" /> was not found.
         /// </exception>
         /// <exception cref="IOException">An I/O error occurred while opening the file. </exception>
-        public FileAttachment(string path, string description = null)
+        public FileAttachment(string path, string description = null, bool isSpoiler = false)
         {
             _isDisposed = false;
             Stream = File.OpenRead(path);
             FileName = Path.GetFileName(path);
             Description = description;
+            IsSpoiler = isSpoiler;
         }
 
         public void Dispose()

src/Discord.Net.Core/Entities/Messages/MessageProperties.cs

@@ -1,3 +1,5 @@
+using System.Collections.Generic;
+
 namespace Discord
 {
     /// <summary>
@@ -48,5 +50,10 @@ namespace Discord
         ///     Gets or sets the allowed mentions of the message.
         /// </summary>
         public Optional<AllowedMentions> AllowedMentions { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the attachments for the message.
+        /// </summary>
+        public Optional<IEnumerable<FileAttachment>> Attachments { get; set; }
     }
 }

src/Discord.Net.Rest/API/Common/Attachment.cs

@@ -8,6 +8,10 @@ namespace Discord.API
         public ulong Id { get; set; }
         [JsonProperty("filename")]
         public string Filename { get; set; }
+        [JsonProperty("description")]
+        public Optional<string> Description { get; set; }
+        [JsonProperty("content_type")]
+        public Optional<string> ContentType { get; set; }
         [JsonProperty("size")]
         public int Size { get; set; }
         [JsonProperty("url")]

src/Discord.Net.Rest/API/Rest/UploadFileParams.cs

@@ -3,6 +3,7 @@ using Discord.Net.Rest;
 using Newtonsoft.Json;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Text;
 
 namespace Discord.API.Rest
@@ -11,9 +12,8 @@ namespace Discord.API.Rest
     {
         private static JsonSerializer _serializer = new JsonSerializer { ContractResolver = new DiscordContractResolver() };
 
-        public Stream File { get; }
+        public FileAttachment[] Files { get; }
 
-        public Optional<string> Filename { get; set; }
         public Optional<string> Content { get; set; }
         public Optional<string> Nonce { get; set; }
         public Optional<bool> IsTTS { get; set; }
@@ -21,22 +21,18 @@ namespace Discord.API.Rest
         public Optional<AllowedMentions> AllowedMentions { get; set; }
         public Optional<MessageReference> MessageReference { get; set; }
         public Optional<ActionRowComponent[]> MessageComponent { get; set; }
+        public Optional<MessageFlags?> Flags { get; set; }
         public Optional<ulong[]> Stickers { get; set; }
-        public bool IsSpoiler { get; set; } = false;
 
-        public UploadFileParams(Stream file)
+        public UploadFileParams(params Discord.FileAttachment[] attachments)
         {
-            File = file;
+            Files = attachments;
         }
 
         public IReadOnlyDictionary<string, object> ToDictionary()
         {
             var d = new Dictionary<string, object>();
-            var filename = Filename.GetValueOrDefault("unknown.dat");
-            if (IsSpoiler && !filename.StartsWith(AttachmentExtensions.SpoilerPrefix))
-                filename = filename.Insert(0, AttachmentExtensions.SpoilerPrefix);
-            d["file"] = new MultipartFile(File, filename);
-
+            
             var payload = new Dictionary<string, object>();
             if (Content.IsSpecified)
                 payload["content"] = Content.Value;
@@ -50,12 +46,33 @@ namespace Discord.API.Rest
                 payload["allowed_mentions"] = AllowedMentions.Value;
             if (MessageComponent.IsSpecified)
                 payload["components"] = MessageComponent.Value;
-            if (IsSpoiler)
-                payload["hasSpoiler"] = IsSpoiler.ToString();
             if (MessageReference.IsSpecified)
                 payload["message_reference"] = MessageReference.Value;
             if (Stickers.IsSpecified)
                 payload["sticker_ids"] = Stickers.Value;
+            if (Flags.IsSpecified)
+                payload["flags"] = Flags;
+
+            List<object> attachments = new();
+
+            for(int n = 0; n != Files.Length; n++)
+            {
+                var attachment = Files[n];
+
+                var filename = attachment.FileName ?? "unknown.dat";
+                if (attachment.IsSpoiler && !filename.StartsWith(AttachmentExtensions.SpoilerPrefix))
+                    filename = filename.Insert(0, AttachmentExtensions.SpoilerPrefix);
+                d[$"files[{n}]"] = new MultipartFile(attachment.Stream, filename);
+
+                attachments.Add(new
+                {
+                    id = (ulong)n,
+                    filename = filename,
+                    description = attachment.Description ?? Optional<string>.Unspecified
+                });
+            }
+
+            payload["attachments"] = attachments;
 
             var json = new StringBuilder();
             using (var text = new StringWriter(json))

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -914,6 +914,19 @@ namespace Discord.API
             var ids = new BucketIds(channelId: channelId);
             return await SendJsonAsync<Message>("PATCH", () => $"channels/{channelId}/messages/{messageId}", args, ids, clientBucket: ClientBucketType.SendEdit, options: options).ConfigureAwait(false);
         }
+
+        public async Task<Message> ModifyMessageAsync(ulong channelId, ulong messageId, Rest.UploadFileParams args, RequestOptions options = null)
+        {
+            Preconditions.NotEqual(channelId, 0, nameof(channelId));
+            Preconditions.NotEqual(messageId, 0, nameof(messageId));
+            Preconditions.NotNull(args, nameof(args));
+            if (args.Content.IsSpecified && args.Content.Value?.Length > DiscordConfig.MaxMessageSize)
+                throw new ArgumentOutOfRangeException($"Message content is too long, length must be less or equal to {DiscordConfig.MaxMessageSize}.", nameof(args.Content));
+            options = RequestOptions.CreateOrClone(options);
+
+            var ids = new BucketIds(channelId: channelId);
+            return await SendMultipartAsync<Message>("PATCH", () => $"channels/{channelId}/messages/{messageId}", args.ToDictionary(), ids, clientBucket: ClientBucketType.SendEdit, options: options).ConfigureAwait(false);
+        }
         #endregion
 
         #region Stickers, Reactions, Crosspost, and Acks

src/Discord.Net.Rest/Entities/Channels/ChannelHelper.cs

@@ -343,8 +343,19 @@ namespace Discord.Rest
         }
 
         /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
-        public static async Task<RestUserMessage> SendFileAsync(IMessageChannel channel, BaseDiscordClient client,
+        public static Task<RestUserMessage> SendFileAsync(IMessageChannel channel, BaseDiscordClient client,
             Stream stream, string filename, string text, bool isTTS, Embed embed, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, RequestOptions options, bool isSpoiler, Embed[] embeds)
+        {
+            return SendFileAsync(channel, client, new FileAttachment(stream, filename, isSpoiler: isSpoiler), text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+        }
+
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public static Task<RestUserMessage> SendFileAsync(IMessageChannel channel, BaseDiscordClient client,
+            FileAttachment attachment, string text, bool isTTS, Embed embed, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, RequestOptions options, Embed[] embeds)
+            => SendFilesAsync(channel, client, new[] { attachment }, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
+        public static async Task<RestUserMessage> SendFilesAsync(IMessageChannel channel, BaseDiscordClient client,
+            IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, RequestOptions options,  Embed[] embeds)
         {
             embeds ??= Array.Empty<Embed>();
             if (embed != null)
@@ -353,7 +364,11 @@ namespace Discord.Rest
             Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
             Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
             Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
-            Preconditions.NotNullOrEmpty(filename, nameof(filename), "File Name must not be empty or null");
+
+            foreach(var attachment in attachments)
+            {
+                Preconditions.NotNullOrEmpty(attachment.FileName, nameof(attachment.FileName), "File Name must not be empty or null");
+            }
 
             // check that user flag and user Id list are exclusive, same with role flag and role Id list
             if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
@@ -376,7 +391,7 @@ namespace Discord.Rest
                 Preconditions.AtMost(stickers.Length, 3, nameof(stickers), "A max of 3 stickers are allowed.");
             }
 
-            var args = new UploadFileParams(stream) { Filename = filename, Content = text, IsTTS = isTTS, Embeds = embeds.Any() ? embeds.Select(x => x.ToModel()).ToArray() : Optional<API.Embed[]>.Unspecified, AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified, MessageReference = messageReference?.ToModel() ?? Optional<API.MessageReference>.Unspecified, MessageComponent = component?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified, IsSpoiler = isSpoiler, Stickers = stickers?.Any() ?? false ? stickers.Select(x => x.Id).ToArray() : Optional<ulong[]>.Unspecified };
+            var args = new UploadFileParams(attachments.ToArray()) { Content = text, IsTTS = isTTS, Embeds = embeds.Any() ? embeds.Select(x => x.ToModel()).ToArray() : Optional<API.Embed[]>.Unspecified, AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified, MessageReference = messageReference?.ToModel() ?? Optional<API.MessageReference>.Unspecified, MessageComponent = component?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified, Stickers = stickers?.Any() ?? false ? stickers.Select(x => x.Id).ToArray() : Optional<ulong[]>.Unspecified };
             var model = await client.ApiClient.UploadFileAsync(channel.Id, args, options).ConfigureAwait(false);
             return RestUserMessage.Create(client, channel, client.CurrentUser, model);
         }

src/Discord.Net.Rest/Entities/Channels/RestDMChannel.cs

@@ -129,6 +129,16 @@ namespace Discord.Rest
         public Task<RestUserMessage> SendFileAsync(Stream stream, string filename, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
             => ChannelHelper.SendFileAsync(this, Discord, stream, filename, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, isSpoiler, embeds);
 
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFileAsync(FileAttachment attachment, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFileAsync(this, Discord, attachment, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFilesAsync(this, Discord, attachments, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
         /// <inheritdoc />
         public Task DeleteMessageAsync(ulong messageId, RequestOptions options = null)
             => ChannelHelper.DeleteMessageAsync(this, messageId, Discord, options);
@@ -215,6 +225,12 @@ namespace Discord.Rest
         async Task<IUserMessage> IMessageChannel.SendFileAsync(Stream stream, string filename, string text, bool isTTS, Embed embed, RequestOptions options, bool isSpoiler, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendFileAsync(stream, filename, text, isTTS, embed, options, isSpoiler, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFileAsync(FileAttachment attachment, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+            => await SendFileAsync(attachment, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+           => await SendFilesAsync(attachments, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
         async Task<IUserMessage> IMessageChannel.SendMessageAsync(string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendMessageAsync(text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         #endregion

src/Discord.Net.Rest/Entities/Channels/RestGroupChannel.cs

@@ -134,7 +134,14 @@ namespace Discord.Rest
         /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
         public Task<RestUserMessage> SendFileAsync(Stream stream, string filename, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
             => ChannelHelper.SendFileAsync(this, Discord, stream, filename, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, isSpoiler, embeds);
-
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFileAsync(FileAttachment attachment, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFileAsync(this, Discord, attachment, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFilesAsync(this, Discord, attachments, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
         /// <inheritdoc />
         public Task TriggerTypingAsync(RequestOptions options = null)
             => ChannelHelper.TriggerTypingAsync(this, Discord, options);
@@ -191,7 +198,10 @@ namespace Discord.Rest
 
         async Task<IUserMessage> IMessageChannel.SendFileAsync(Stream stream, string filename, string text, bool isTTS, Embed embed, RequestOptions options, bool isSpoiler, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendFileAsync(stream, filename, text, isTTS, embed, options, isSpoiler, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
-
+        async Task<IUserMessage> IMessageChannel.SendFileAsync(FileAttachment attachment, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+            => await SendFileAsync(attachment, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        async Task<IUserMessage> IMessageChannel.SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+           => await SendFilesAsync(attachments, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         async Task<IUserMessage> IMessageChannel.SendMessageAsync(string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendMessageAsync(text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         #endregion

src/Discord.Net.Rest/Entities/Channels/RestTextChannel.cs

@@ -139,6 +139,16 @@ namespace Discord.Rest
         public Task<RestUserMessage> SendFileAsync(Stream stream, string filename, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
             => ChannelHelper.SendFileAsync(this, Discord, stream, filename, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, isSpoiler, embeds);
 
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFileAsync(FileAttachment attachment, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFileAsync(this, Discord, attachment, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFilesAsync(this, Discord, attachments, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
         /// <inheritdoc />
         public Task DeleteMessageAsync(ulong messageId, RequestOptions options = null)
             => ChannelHelper.DeleteMessageAsync(this, messageId, Discord, options);
@@ -325,6 +335,15 @@ namespace Discord.Rest
         /// <inheritdoc />
         async Task<IUserMessage> IMessageChannel.SendFileAsync(Stream stream, string filename, string text, bool isTTS, Embed embed, RequestOptions options, bool isSpoiler, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendFileAsync(stream, filename, text, isTTS, embed, options, isSpoiler, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+
+        /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFileAsync(FileAttachment attachment, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+            => await SendFileAsync(attachment, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+
+        /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+           => await SendFilesAsync(attachments, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+
         /// <inheritdoc />
         async Task<IUserMessage> IMessageChannel.SendMessageAsync(string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendMessageAsync(text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);

src/Discord.Net.Rest/Entities/Messages/MessageHelper.cs

@@ -25,71 +25,9 @@ namespace Discord.Rest
 
         /// <exception cref="InvalidOperationException">Only the author of a message may modify the message.</exception>
         /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
-        public static async Task<Model> ModifyAsync(IMessage msg, BaseDiscordClient client, Action<MessageProperties> func,
+        public static Task<Model> ModifyAsync(IMessage msg, BaseDiscordClient client, Action<MessageProperties> func,
             RequestOptions options)
-        {
-            var args = new MessageProperties();
-            func(args);
-
-            if (msg.Author.Id != client.CurrentUser.Id && (args.Content.IsSpecified || args.Embeds.IsSpecified || args.AllowedMentions.IsSpecified))
-                throw new InvalidOperationException("Only the author of a message may modify the message content, embed, or allowed mentions.");
-
-            var embed = args.Embed;
-            var embeds = args.Embeds;
-
-            bool hasText = args.Content.IsSpecified ? !string.IsNullOrEmpty(args.Content.Value) : !string.IsNullOrEmpty(msg.Content);
-            bool hasEmbeds = embed.IsSpecified && embed.Value != null || embeds.IsSpecified && embeds.Value?.Length > 0 || msg.Embeds.Any();
-
-            if (!hasText && !hasEmbeds)
-                Preconditions.NotNullOrEmpty(args.Content.IsSpecified ? args.Content.Value : string.Empty, nameof(args.Content));
-
-            if (args.AllowedMentions.IsSpecified)
-            {
-                AllowedMentions allowedMentions = args.AllowedMentions.Value;
-                Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
-                Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
-
-                // check that user flag and user Id list are exclusive, same with role flag and role Id list
-                if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
-                {
-                    if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users) &&
-                        allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
-                    {
-                        throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(allowedMentions));
-                    }
-
-                    if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles) &&
-                        allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
-                    {
-                        throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(allowedMentions));
-                    }
-                }
-            }
-
-            var apiEmbeds = embed.IsSpecified || embeds.IsSpecified ? new List<API.Embed>() : null;
-
-            if (embed.IsSpecified && embed.Value != null)
-            {
-                apiEmbeds.Add(embed.Value.ToModel());
-            }
-
-            if (embeds.IsSpecified && embeds.Value != null)
-            {
-                apiEmbeds.AddRange(embeds.Value.Select(x => x.ToModel()));
-            }
-
-            Preconditions.AtMost(apiEmbeds?.Count ?? 0, 10, nameof(args.Embeds), "A max of 10 embeds are allowed.");
-
-            var apiArgs = new ModifyMessageParams
-            {
-                Content = args.Content,
-                Embeds = apiEmbeds?.ToArray() ?? Optional<API.Embed[]>.Unspecified,
-                Components = args.Components.IsSpecified ? args.Components.Value?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Array.Empty<API.ActionRowComponent>() : Optional<API.ActionRowComponent[]>.Unspecified,
-                Flags = args.Flags,
-                AllowedMentions = args.AllowedMentions.IsSpecified ? args.AllowedMentions.Value.ToModel() : Optional<API.AllowedMentions>.Unspecified,
-            };
-            return await client.ApiClient.ModifyMessageAsync(msg.Channel.Id, msg.Id, apiArgs, options).ConfigureAwait(false);
-        }
+            => ModifyAsync(msg.Channel.Id, msg.Id, client, func, options);
 
         public static async Task<Model> ModifyAsync(ulong channelId, ulong msgId, BaseDiscordClient client, Action<MessageProperties> func,
             RequestOptions options)
@@ -103,8 +41,9 @@ namespace Discord.Rest
             bool hasText = args.Content.IsSpecified && string.IsNullOrEmpty(args.Content.Value);
             bool hasEmbeds = embed.IsSpecified && embed.Value != null || embeds.IsSpecified && embeds.Value?.Length > 0;
             bool hasComponents = args.Components.IsSpecified && args.Components.Value != null;
+            bool hasAttachments = args.Attachments.IsSpecified;
 
-            if (!hasComponents && !hasText && !hasEmbeds)
+            if (!hasComponents && !hasText && !hasEmbeds && !hasAttachments)
                 Preconditions.NotNullOrEmpty(args.Content.IsSpecified ? args.Content.Value : string.Empty, nameof(args.Content));
 
             if (args.AllowedMentions.IsSpecified)
@@ -145,15 +84,31 @@ namespace Discord.Rest
 
             Preconditions.AtMost(apiEmbeds?.Count ?? 0, 10, nameof(args.Embeds), "A max of 10 embeds are allowed.");
 
-            var apiArgs = new API.Rest.ModifyMessageParams
+            if(!args.Attachments.IsSpecified)
+            {
+                var apiArgs = new API.Rest.ModifyMessageParams
+                {
+                    Content = args.Content,
+                    Embeds = apiEmbeds?.ToArray() ?? Optional<API.Embed[]>.Unspecified,
+                    Flags = args.Flags.IsSpecified ? args.Flags.Value : Optional.Create<MessageFlags?>(),
+                    AllowedMentions = args.AllowedMentions.IsSpecified ? args.AllowedMentions.Value.ToModel() : Optional.Create<API.AllowedMentions>(),
+                    Components = args.Components.IsSpecified ? args.Components.Value?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Array.Empty<API.ActionRowComponent>() : Optional<API.ActionRowComponent[]>.Unspecified,
+                };
+                return await client.ApiClient.ModifyMessageAsync(channelId, msgId, apiArgs, options).ConfigureAwait(false);
+            }
+            else
             {
-                Content = args.Content,
-                Embeds = apiEmbeds?.ToArray() ?? Optional<API.Embed[]>.Unspecified,
-                Flags = args.Flags.IsSpecified ? args.Flags.Value : Optional.Create<MessageFlags?>(),
-                AllowedMentions = args.AllowedMentions.IsSpecified ? args.AllowedMentions.Value.ToModel() : Optional.Create<API.AllowedMentions>(),
-                Components = args.Components.IsSpecified ? args.Components.Value?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Array.Empty<API.ActionRowComponent>() : Optional<API.ActionRowComponent[]>.Unspecified,
-            };
-            return await client.ApiClient.ModifyMessageAsync(channelId, msgId, apiArgs, options).ConfigureAwait(false);
+                var apiArgs = new UploadFileParams(args.Attachments.Value.ToArray())
+                {
+                    Content = args.Content,
+                    Embeds = apiEmbeds?.ToArray() ?? Optional<API.Embed[]>.Unspecified,
+                    Flags = args.Flags.IsSpecified ? args.Flags.Value : Optional.Create<MessageFlags?>(),
+                    AllowedMentions = args.AllowedMentions.IsSpecified ? args.AllowedMentions.Value.ToModel() : Optional.Create<API.AllowedMentions>(),
+                    MessageComponent = args.Components.IsSpecified ? args.Components.Value?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Array.Empty<API.ActionRowComponent>() : Optional<API.ActionRowComponent[]>.Unspecified
+                };
+
+                return await client.ApiClient.ModifyMessageAsync(channelId, msgId, apiArgs, options).ConfigureAwait(false);
+            }
         }
 
         public static Task DeleteAsync(IMessage msg, BaseDiscordClient client, RequestOptions options)

src/Discord.Net.WebSocket/Entities/Channels/SocketDMChannel.cs

@@ -150,6 +150,15 @@ namespace Discord.WebSocket
         public Task<RestUserMessage> SendFileAsync(Stream stream, string filename, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
             => ChannelHelper.SendFileAsync(this, Discord, stream, filename, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, isSpoiler, embeds);
         /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFileAsync(FileAttachment attachment, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFileAsync(this, Discord, attachment, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFilesAsync(this, Discord, attachments, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
+        /// <inheritdoc />
         public Task DeleteMessageAsync(ulong messageId, RequestOptions options = null)
             => ChannelHelper.DeleteMessageAsync(this, messageId, Discord, options);
         /// <inheritdoc />
@@ -252,6 +261,12 @@ namespace Discord.WebSocket
         async Task<IUserMessage> IMessageChannel.SendFileAsync(Stream stream, string filename, string text, bool isTTS, Embed embed, RequestOptions options, bool isSpoiler, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendFileAsync(stream, filename, text, isTTS, embed, options, isSpoiler, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFileAsync(FileAttachment attachment, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+            => await SendFileAsync(attachment, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+           => await SendFilesAsync(attachments, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
         async Task<IUserMessage> IMessageChannel.SendMessageAsync(string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendMessageAsync(text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         #endregion

src/Discord.Net.WebSocket/Entities/Channels/SocketGroupChannel.cs

@@ -183,6 +183,14 @@ namespace Discord.WebSocket
         /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
         public Task<RestUserMessage> SendFileAsync(Stream stream, string filename, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
             => ChannelHelper.SendFileAsync(this, Discord, stream, filename, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, isSpoiler, embeds);
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFileAsync(FileAttachment attachment, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFileAsync(this, Discord, attachment, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFilesAsync(this, Discord, attachments, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
 
         /// <inheritdoc />
         public Task DeleteMessageAsync(ulong messageId, RequestOptions options = null)
@@ -320,6 +328,13 @@ namespace Discord.WebSocket
         async Task<IUserMessage> IMessageChannel.SendFileAsync(Stream stream, string filename, string text, bool isTTS, Embed embed, RequestOptions options, bool isSpoiler, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendFileAsync(stream, filename, text, isTTS, embed, options, isSpoiler, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFileAsync(FileAttachment attachment, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+            => await SendFileAsync(attachment, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+           => await SendFilesAsync(attachments, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+
+        /// <inheritdoc />
         async Task<IUserMessage> IMessageChannel.SendMessageAsync(string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendMessageAsync(text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         #endregion

src/Discord.Net.WebSocket/Entities/Channels/SocketTextChannel.cs

@@ -223,6 +223,16 @@ namespace Discord.WebSocket
         public Task<RestUserMessage> SendFileAsync(Stream stream, string filename, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
             => ChannelHelper.SendFileAsync(this, Discord, stream, filename, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, isSpoiler, embeds);
 
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFileAsync(FileAttachment attachment, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFileAsync(this, Discord, attachment, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
+        /// <inheritdoc />
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        public Task<RestUserMessage> SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS = false, Embed embed = null, RequestOptions options = null, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null)
+            => ChannelHelper.SendFilesAsync(this, Discord, attachments, text, isTTS, embed, allowedMentions, messageReference, component, stickers, options, embeds);
+
         /// <inheritdoc />
         public Task DeleteMessagesAsync(IEnumerable<IMessage> messages, RequestOptions options = null)
             => ChannelHelper.DeleteMessagesAsync(this, Discord, messages.Select(x => x.Id), options);
@@ -377,6 +387,12 @@ namespace Discord.WebSocket
         async Task<IUserMessage> IMessageChannel.SendFileAsync(Stream stream, string filename, string text, bool isTTS, Embed embed, RequestOptions options, bool isSpoiler, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendFileAsync(stream, filename, text, isTTS, embed, options, isSpoiler, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFileAsync(FileAttachment attachment, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+            => await SendFileAsync(attachment, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
+        async Task<IUserMessage> IMessageChannel.SendFilesAsync(IEnumerable<FileAttachment> attachments, string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
+           => await SendFilesAsync(attachments, text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
+        /// <inheritdoc />
         async Task<IUserMessage> IMessageChannel.SendMessageAsync(string text, bool isTTS, Embed embed, RequestOptions options, AllowedMentions allowedMentions, MessageReference messageReference, MessageComponent component, ISticker[] stickers, Embed[] embeds)
             => await SendMessageAsync(text, isTTS, embed, options, allowedMentions, messageReference, component, stickers, embeds).ConfigureAwait(false);
         #endregion

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

@@ -86,5 +86,7 @@ namespace Discord
         public Task<IUserMessage> SendMessageAsync(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) => throw new NotImplementedException();
         public Task<IUserMessage> SendFileAsync(string filePath, string text = null, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null) => throw new NotImplementedException();
         public Task<IUserMessage> SendFileAsync(Stream stream, string filename, string text = null, bool isTTS = false, Embed embed = null, RequestOptions options = null, bool isSpoiler = false, AllowedMentions allowedMentions = null, MessageReference messageReference = null, MessageComponent component = null, ISticker[] stickers = null, Embed[] embeds = null) => 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) => 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) => throw new NotImplementedException();
     }
 }

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

@@ -105,5 +105,8 @@ 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) => 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) => throw new NotImplementedException();
     }
 }

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

@@ -212,5 +212,7 @@ namespace Discord
         }
 
         public Task<IThreadChannel> CreateThreadAsync(string name, ThreadType type = ThreadType.PublicThread, ThreadArchiveDuration autoArchiveDuration = ThreadArchiveDuration.OneDay, IMessage message = null, RequestOptions options = null) => 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) => 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) => throw new NotImplementedException();
     }
 }