types: Use readonly arrays and const type parameters in places (#9641)

* types: wrap arrays in `Readonly<>`

* refactor: prefer `readonly` syntax

Co-authored-by: Almeida <almeidx@pm.me>

* types: `const` type parameters

* test: add tests

* fix: fix more instances

---------

Co-authored-by: Almeida <almeidx@pm.me>

packages/discord.js/typings/index.d.ts

@@ -1162,10 +1162,10 @@ export class CommandInteractionOptionResolver<Cached extends CacheType = CacheTy
   public getSubcommandGroup(required?: boolean): string | null;
   public getBoolean(name: string, required: true): boolean;
   public getBoolean(name: string, required?: boolean): boolean | null;
-  public getChannel<T extends ChannelType = ChannelType>(
+  public getChannel<const T extends ChannelType = ChannelType>(
     name: string,
     required: true,
-    channelTypes?: T[],
+    channelTypes?: readonly T[],
   ): Extract<
     NonNullable<CommandInteractionOption<Cached>['channel']>,
     {
@@ -1177,10 +1177,10 @@ export class CommandInteractionOptionResolver<Cached extends CacheType = CacheTy
         : T;
     }
   >;
-  public getChannel<T extends ChannelType = ChannelType>(
+  public getChannel<const T extends ChannelType = ChannelType>(
     name: string,
     required?: boolean,
-    channelTypes?: T[],
+    channelTypes?: readonly T[],
   ): Extract<
     NonNullable<CommandInteractionOption<Cached>['channel']>,
     {
@@ -3713,9 +3713,11 @@ export class ApplicationCommandManager<
     id?: Snowflake,
     options?: FetchApplicationCommandOptions,
   ): Promise<Collection<Snowflake, ApplicationCommandScope>>;
-  public set(commands: ApplicationCommandDataResolvable[]): Promise<Collection<Snowflake, ApplicationCommandScope>>;
   public set(
-    commands: ApplicationCommandDataResolvable[],
+    commands: readonly ApplicationCommandDataResolvable[],
+  ): Promise<Collection<Snowflake, ApplicationCommandScope>>;
+  public set(
+    commands: readonly ApplicationCommandDataResolvable[],
     guildId: Snowflake,
   ): Promise<Collection<Snowflake, ApplicationCommand>>;
   private static transformCommand(command: ApplicationCommandDataResolvable): RESTPostAPIApplicationCommandsJSONBody;
@@ -3748,21 +3750,21 @@ export class ApplicationCommandPermissionsManager<
     options:
       | (FetchSingleOptions & {
           token: string;
-          channels?: (GuildChannelResolvable | ChannelPermissionConstant)[];
+          channels?: readonly (GuildChannelResolvable | ChannelPermissionConstant)[];
-          roles?: (RoleResolvable | RolePermissionConstant)[];
+          roles?: readonly (RoleResolvable | RolePermissionConstant)[];
-          users: UserResolvable[];
+          users: readonly UserResolvable[];
         })
       | (FetchSingleOptions & {
           token: string;
-          channels?: (GuildChannelResolvable | ChannelPermissionConstant)[];
+          channels?: readonly (GuildChannelResolvable | ChannelPermissionConstant)[];
-          roles: (RoleResolvable | RolePermissionConstant)[];
+          roles: readonly (RoleResolvable | RolePermissionConstant)[];
-          users?: UserResolvable[];
+          users?: readonly UserResolvable[];
         })
       | (FetchSingleOptions & {
           token: string;
-          channels: (GuildChannelResolvable | ChannelPermissionConstant)[];
+          channels: readonly (GuildChannelResolvable | ChannelPermissionConstant)[];
-          roles?: (RoleResolvable | RolePermissionConstant)[];
+          roles?: readonly (RoleResolvable | RolePermissionConstant)[];
-          users?: UserResolvable[];
+          users?: readonly UserResolvable[];
         }),
   ): Promise<ApplicationCommandPermissions[]>;
   public set(
@@ -4321,7 +4323,7 @@ export interface ChatInputApplicationCommandData extends BaseApplicationCommandD
   description: string;
   descriptionLocalizations?: LocalizationMap;
   type?: ApplicationCommandType.ChatInput;
-  options?: ApplicationCommandOptionData[];
+  options?: readonly ApplicationCommandOptionData[];
 }
 
 export type ApplicationCommandData =
@@ -4331,13 +4333,13 @@ export type ApplicationCommandData =
 
 export interface ApplicationCommandChannelOptionData extends BaseApplicationCommandOptionsData {
   type: CommandOptionChannelResolvableType;
-  channelTypes?: ApplicationCommandOptionAllowedChannelTypes[];
+  channelTypes?: readonly ApplicationCommandOptionAllowedChannelTypes[];
-  channel_types?: ApplicationCommandOptionAllowedChannelTypes[];
+  channel_types?: readonly ApplicationCommandOptionAllowedChannelTypes[];
 }
 
 export interface ApplicationCommandChannelOption extends BaseApplicationCommandOptionsData {
   type: ApplicationCommandOptionType.Channel;
-  channelTypes?: ApplicationCommandOptionAllowedChannelTypes[];
+  channelTypes?: readonly ApplicationCommandOptionAllowedChannelTypes[];
 }
 
 export interface ApplicationCommandRoleOptionData extends BaseApplicationCommandOptionsData {
@@ -4407,14 +4409,14 @@ export interface ApplicationCommandAutocompleteStringOptionData
 export interface ApplicationCommandChoicesData<Type extends string | number = string | number>
   extends Omit<BaseApplicationCommandOptionsData, 'autocomplete'> {
   type: CommandOptionChoiceResolvableType;
-  choices?: ApplicationCommandOptionChoiceData<Type>[];
+  choices?: readonly ApplicationCommandOptionChoiceData<Type>[];
   autocomplete?: false;
 }
 
 export interface ApplicationCommandChoicesOption<Type extends string | number = string | number>
   extends Omit<BaseApplicationCommandOptionsData, 'autocomplete'> {
   type: CommandOptionChoiceResolvableType;
-  choices?: ApplicationCommandOptionChoiceData<Type>[];
+  choices?: readonly ApplicationCommandOptionChoiceData<Type>[];
   autocomplete?: false;
 }
 
@@ -4456,22 +4458,25 @@ export interface ApplicationCommandBooleanOption extends BaseApplicationCommandO
 
 export interface ApplicationCommandSubGroupData extends Omit<BaseApplicationCommandOptionsData, 'required'> {
   type: ApplicationCommandOptionType.SubcommandGroup;
-  options: ApplicationCommandSubCommandData[];
+  options: readonly ApplicationCommandSubCommandData[];
 }
 
 export interface ApplicationCommandSubGroup extends Omit<BaseApplicationCommandOptionsData, 'required'> {
   type: ApplicationCommandOptionType.SubcommandGroup;
-  options?: ApplicationCommandSubCommand[];
+  options?: readonly ApplicationCommandSubCommand[];
 }
 
 export interface ApplicationCommandSubCommandData extends Omit<BaseApplicationCommandOptionsData, 'required'> {
   type: ApplicationCommandOptionType.Subcommand;
-  options?: Exclude<ApplicationCommandOptionData, ApplicationCommandSubGroupData | ApplicationCommandSubCommandData>[];
+  options?: readonly Exclude<
+    ApplicationCommandOptionData,
+    ApplicationCommandSubGroupData | ApplicationCommandSubCommandData
+  >[];
 }
 
 export interface ApplicationCommandSubCommand extends Omit<BaseApplicationCommandOptionsData, 'required'> {
   type: ApplicationCommandOptionType.Subcommand;
-  options?: Exclude<ApplicationCommandOption, ApplicationCommandSubGroup | ApplicationCommandSubCommand>[];
+  options?: readonly Exclude<ApplicationCommandOption, ApplicationCommandSubGroup | ApplicationCommandSubCommand>[];
 }
 
 export interface ApplicationCommandNonOptionsData extends BaseApplicationCommandOptionsData {
@@ -4527,11 +4532,11 @@ export interface ApplicationCommandPermissionsUpdateData {
   id: Snowflake;
   guildId: Snowflake;
   applicationId: Snowflake;
-  permissions: ApplicationCommandPermissions[];
+  permissions: readonly ApplicationCommandPermissions[];
 }
 
 export interface EditApplicationCommandPermissionsMixin {
-  permissions: ApplicationCommandPermissions[];
+  permissions: readonly ApplicationCommandPermissions[];
   token: string;
 }
 

packages/discord.js/typings/index.test-d.ts

@@ -163,6 +163,14 @@ import {
   ThreadManager,
   FetchedThreads,
   FetchedThreadsMore,
+  ApplicationCommandChannelOptionData,
+  ApplicationCommandChannelOption,
+  ApplicationCommandChoicesOption,
+  ApplicationCommandChoicesData,
+  ApplicationCommandSubGroup,
+  ApplicationCommandSubCommand,
+  ChatInputApplicationCommandData,
+  ApplicationCommandPermissionsManager,
 } from '.';
 import { expectAssignable, expectNotAssignable, expectNotType, expectType } from 'tsd';
 import type { ContextMenuCommandBuilder, SlashCommandBuilder } from '@discordjs/builders';
@@ -1355,7 +1363,7 @@ declare const applicationCommandManager: ApplicationCommandManager;
     applicationCommandManager.set([applicationCommandData]),
   );
   expectType<Promise<Collection<Snowflake, ApplicationCommand>>>(
-    applicationCommandManager.set([applicationCommandData], '0'),
+    applicationCommandManager.set([applicationCommandData] as const, '0'),
   );
 
   // Test inference of choice values.
@@ -1377,6 +1385,41 @@ declare const applicationCommandManager: ApplicationCommandManager;
   }
 }
 
+declare const applicationCommandPermissionsManager: ApplicationCommandPermissionsManager<
+  {},
+  {},
+  Guild | null,
+  Snowflake
+>;
+{
+  applicationCommandPermissionsManager.add({ permissions: [], token: '' });
+  applicationCommandPermissionsManager.add({ permissions: [] as const, token: '' });
+  applicationCommandPermissionsManager.set({ permissions: [], token: '' });
+  applicationCommandPermissionsManager.set({ permissions: [] as const, token: '' });
+  applicationCommandPermissionsManager.remove({ channels: [], roles: [], users: [], token: '' });
+
+  applicationCommandPermissionsManager.remove({
+    channels: [] as const,
+    roles: [] as const,
+    users: [] as const,
+    token: '',
+  });
+}
+
+declare const chatInputApplicationCommandData: ChatInputApplicationCommandData;
+{
+  chatInputApplicationCommandData.options = [];
+  chatInputApplicationCommandData.options = [] as const;
+}
+
+declare const applicationCommandChannelOptionData: ApplicationCommandChannelOptionData;
+declare const applicationCommandChannelOption: ApplicationCommandChannelOption;
+{
+  applicationCommandChannelOptionData.channelTypes = [] as const;
+  applicationCommandChannelOptionData.channel_types = [] as const;
+  applicationCommandChannelOption.channelTypes = [] as const;
+}
+
 declare const applicationNonChoiceOptionData: ApplicationCommandOptionData & {
   type: CommandOptionNonChoiceResolvableType;
 };
@@ -1387,10 +1430,32 @@ declare const applicationNonChoiceOptionData: ApplicationCommandOptionData & {
   applicationNonChoiceOptionData.choices;
 }
 
+declare const applicationCommandChoicesData: ApplicationCommandChoicesData;
+declare const applicationCommandChoicesOption: ApplicationCommandChoicesOption;
+{
+  applicationCommandChoicesData.choices = [];
+  applicationCommandChoicesData.choices = [] as const;
+  applicationCommandChoicesOption.choices = [];
+  applicationCommandChoicesOption.choices = [] as const;
+}
+
+declare const applicationCommandSubCommandData: ApplicationCommandSubCommandData;
+declare const applicationCommandSubCommand: ApplicationCommandSubCommand;
+{
+  applicationCommandSubCommandData.options = [];
+  applicationCommandSubCommandData.options = [] as const;
+  applicationCommandSubCommand.options = [];
+  applicationCommandSubCommand.options = [] as const;
+}
+
 declare const applicationSubGroupCommandData: ApplicationCommandSubGroupData;
+declare const applicationCommandSubGroup: ApplicationCommandSubGroup;
 {
   expectType<ApplicationCommandOptionType.SubcommandGroup>(applicationSubGroupCommandData.type);
-  expectType<ApplicationCommandSubCommandData[]>(applicationSubGroupCommandData.options);
+  applicationSubGroupCommandData.options = [];
+  applicationSubGroupCommandData.options = [] as const;
+  applicationCommandSubGroup.options = [];
+  applicationCommandSubGroup.options = [] as const;
 }
 
 declare const autoModerationRuleManager: AutoModerationRuleManager;
@@ -1814,6 +1879,7 @@ client.on('interactionCreate', async interaction => {
       expectType<ForumChannel | VoiceChannel>(
         interaction.options.getChannel('test', true, [ChannelType.GuildForum, ChannelType.GuildVoice]),
       );
+      expectType<TextChannel>(interaction.options.getChannel('test', true, [ChannelType.GuildText] as const));
       expectType<ForumChannel | VoiceChannel | null>(
         interaction.options.getChannel('test', false, [ChannelType.GuildForum, ChannelType.GuildVoice]),
       );