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/comments/comments.service.spec.ts

@@ -0,0 +1,82 @@
+import { ForbiddenException, NotFoundException } from "@nestjs/common";
+import { Test, TestingModule } from "@nestjs/testing";
+import { CommentsService } from "./comments.service";
+import { CommentsRepository } from "./repositories/comments.repository";
+
+describe("CommentsService", () => {
+	let service: CommentsService;
+	let repository: CommentsRepository;
+
+	const mockCommentsRepository = {
+		create: jest.fn(),
+		findAllByContentId: jest.fn(),
+		findOne: jest.fn(),
+		delete: jest.fn(),
+	};
+
+	beforeEach(async () => {
+		const module: TestingModule = await Test.createTestingModule({
+			providers: [
+				CommentsService,
+				{ provide: CommentsRepository, useValue: mockCommentsRepository },
+			],
+		}).compile();
+
+		service = module.get<CommentsService>(CommentsService);
+		repository = module.get<CommentsRepository>(CommentsRepository);
+	});
+
+	it("should be defined", () => {
+		expect(service).toBeDefined();
+	});
+
+	describe("create", () => {
+		it("should create a comment", async () => {
+			const userId = "user1";
+			const contentId = "content1";
+			const dto = { text: "Nice meme" };
+			mockCommentsRepository.create.mockResolvedValue({ id: "c1", ...dto });
+
+			const result = await service.create(userId, contentId, dto);
+			expect(result.id).toBe("c1");
+			expect(repository.create).toHaveBeenCalledWith({
+				userId,
+				contentId,
+				text: dto.text,
+			});
+		});
+	});
+
+	describe("findAllByContentId", () => {
+		it("should return comments for a content", async () => {
+			mockCommentsRepository.findAllByContentId.mockResolvedValue([{ id: "c1" }]);
+			const result = await service.findAllByContentId("content1");
+			expect(result).toHaveLength(1);
+			expect(repository.findAllByContentId).toHaveBeenCalledWith("content1");
+		});
+	});
+
+	describe("remove", () => {
+		it("should remove comment if owner", async () => {
+			mockCommentsRepository.findOne.mockResolvedValue({ userId: "u1" });
+			await service.remove("u1", "c1");
+			expect(repository.delete).toHaveBeenCalledWith("c1");
+		});
+
+		it("should remove comment if admin", async () => {
+			mockCommentsRepository.findOne.mockResolvedValue({ userId: "u1" });
+			await service.remove("other", "c1", true);
+			expect(repository.delete).toHaveBeenCalledWith("c1");
+		});
+
+		it("should throw NotFoundException if comment does not exist", async () => {
+			mockCommentsRepository.findOne.mockResolvedValue(null);
+			await expect(service.remove("u1", "c1")).rejects.toThrow(NotFoundException);
+		});
+
+		it("should throw ForbiddenException if not owner and not admin", async () => {
+			mockCommentsRepository.findOne.mockResolvedValue({ userId: "u1" });
+			await expect(service.remove("other", "c1")).rejects.toThrow(ForbiddenException);
+		});
+	});
+});