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/realtime/events.gateway.spec.ts

@@ -0,0 +1,52 @@
+import { ConfigService } from "@nestjs/config";
+import { Test, TestingModule } from "@nestjs/testing";
+import { Server } from "socket.io";
+import { JwtService } from "../crypto/services/jwt.service";
+import { EventsGateway } from "./events.gateway";
+
+describe("EventsGateway", () => {
+	let gateway: EventsGateway;
+	let jwtService: JwtService;
+
+	const mockJwtService = {
+		verifyJwt: jest.fn(),
+	};
+
+	const mockConfigService = {
+		get: jest.fn().mockReturnValue("secret-password-32-chars-long-!!!"),
+	};
+
+	beforeEach(async () => {
+		const module: TestingModule = await Test.createTestingModule({
+			providers: [
+				EventsGateway,
+				{ provide: JwtService, useValue: mockJwtService },
+				{ provide: ConfigService, useValue: mockConfigService },
+			],
+		}).compile();
+
+		gateway = module.get<EventsGateway>(EventsGateway);
+		jwtService = module.get<JwtService>(JwtService);
+		gateway.server = {
+			to: jest.fn().mockReturnThis(),
+			emit: jest.fn(),
+		} as any;
+	});
+
+	it("should be defined", () => {
+		expect(gateway).toBeDefined();
+	});
+
+	describe("sendToUser", () => {
+		it("should emit event to user room", () => {
+			const userId = "user123";
+			const event = "test_event";
+			const data = { foo: "bar" };
+
+			gateway.sendToUser(userId, event, data);
+
+			expect(gateway.server.to).toHaveBeenCalledWith(`user:${userId}`);
+			expect(gateway.server.to(`user:${userId}`).emit).toHaveBeenCalledWith(event, data);
+		});
+	});
+});