feat(NewsChannel): add support for following (#4805)

Co-authored-by: Sugden <28943913+NotSugden@users.noreply.github.com>

src/structures/NewsChannel.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const TextChannel = require('./TextChannel');
+const { Error } = require('../errors');
 
 /**
  * Represents a guild news channel on Discord.
@@ -13,6 +14,25 @@ class NewsChannel extends TextChannel {
     // News channels don't have a rate limit per user, remove it
     this.rateLimitPerUser = undefined;
   }
+
+  /**
+   * Adds the target to this channel's followers.
+   * @param {GuildChannelResolvable} channel The channel where the webhook should be created
+   * @param {string} [reason] Reason for creating the webhook
+   * @returns {Promise<NewsChannel>}
+   * @example
+   * if (channel.type === 'news') {
+   *   channel.addFollower('222197033908436994', 'Important announcements')
+   *     .then(() => console.log('Added follower'))
+   *     .catch(console.error);
+   * }
+   */
+  async addFollower(channel, reason) {
+    const channelID = this.guild.channels.resolveID(channel);
+    if (!channelID) throw new Error('GUILD_CHANNEL_RESOLVE');
+    await this.client.api.channels(this.id).followers.post({ data: { webhook_channel_id: channelID }, reason });
+    return this;
+  }
 }
 
 module.exports = NewsChannel;

typings/index.d.ts

@@ -1187,6 +1187,7 @@ declare module 'discord.js' {
     ): Promise<Webhook>;
     public setNSFW(nsfw: boolean, reason?: string): Promise<NewsChannel>;
     public fetchWebhooks(): Promise<Collection<Snowflake, Webhook>>;
+    public addFollower(channel: GuildChannelResolvable, reason?: string): Promise<NewsChannel>;
   }
 
   export class PartialGroupDMChannel extends Channel {