test: add unit tests for messaging, comments, events, and user services

- Added comprehensive unit tests for `MessagesService`, `CommentsService`, `EventsGateway`, and enhancements in `UsersService`.
- Ensured proper mocking and test coverage for newly introduced dependencies like `EventsGateway` and `RBACService`.

backend/src/contents/contents.service.spec.ts

@@ -7,6 +7,7 @@ import { BadRequestException } from "@nestjs/common";
 import { ConfigService } from "@nestjs/config";
 import { Test, TestingModule } from "@nestjs/testing";
 import { MediaService } from "../media/media.service";
+import { EventsGateway } from "../realtime/events.gateway";
 import { S3Service } from "../s3/s3.service";
 import { ContentsService } from "./contents.service";
 import { ContentsRepository } from "./repositories/contents.repository";
@@ -49,6 +50,10 @@ describe("ContentsService", () => {
 		del: jest.fn(),
 	};
 
+	const mockEventsGateway = {
+		sendToUser: jest.fn(),
+	};
+
 	beforeEach(async () => {
 		jest.clearAllMocks();
 
@@ -60,6 +65,7 @@ describe("ContentsService", () => {
 				{ provide: MediaService, useValue: mockMediaService },
 				{ provide: ConfigService, useValue: mockConfigService },
 				{ provide: CACHE_MANAGER, useValue: mockCacheManager },
+				{ provide: EventsGateway, useValue: mockEventsGateway },
 			],
 		}).compile();