test(favorites): add unit tests for FavoritesController and FavoritesRepository with mocked dependencies

backend/src/favorites/repositories/favorites.repository.spec.ts

@@ -0,0 +1,68 @@
+import { Test, TestingModule } from "@nestjs/testing";
+import { DatabaseService } from "../../database/database.service";
+import { FavoritesRepository } from "./favorites.repository";
+
+describe("FavoritesRepository", () => {
+	let repository: FavoritesRepository;
+
+	const mockDb = {
+		select: jest.fn().mockReturnThis(),
+		from: jest.fn().mockReturnThis(),
+		innerJoin: jest.fn().mockReturnThis(),
+		where: jest.fn().mockReturnThis(),
+		limit: jest.fn().mockReturnThis(),
+		offset: jest.fn().mockReturnThis(),
+		insert: jest.fn().mockReturnThis(),
+		values: jest.fn().mockReturnThis(),
+		delete: jest.fn().mockReturnThis(),
+		returning: jest.fn().mockReturnThis(),
+		execute: jest.fn(),
+	};
+
+	const wrapWithThen = (obj: any) => {
+		obj.then = function (onFulfilled: any) {
+			const result = this.execute();
+			return Promise.resolve(result).then(onFulfilled);
+		};
+		return obj;
+	};
+	wrapWithThen(mockDb);
+
+	beforeEach(async () => {
+		const module: TestingModule = await Test.createTestingModule({
+			providers: [
+				FavoritesRepository,
+				{ provide: DatabaseService, useValue: { db: mockDb } },
+			],
+		}).compile();
+
+		repository = module.get<FavoritesRepository>(FavoritesRepository);
+	});
+
+	it("should find content by id", async () => {
+		(mockDb.execute as jest.Mock).mockResolvedValue([{ id: "1" }]);
+		const result = await repository.findContentById("1");
+		expect(result.id).toBe("1");
+	});
+
+	it("should add favorite", async () => {
+		(mockDb.execute as jest.Mock).mockResolvedValue([
+			{ userId: "u", contentId: "c" },
+		]);
+		await repository.add("u", "c");
+		expect(mockDb.insert).toHaveBeenCalled();
+	});
+
+	it("should remove favorite", async () => {
+		(mockDb.execute as jest.Mock).mockResolvedValue([{ id: "1" }]);
+		await repository.remove("u", "c");
+		expect(mockDb.delete).toHaveBeenCalled();
+	});
+
+	it("should find by user id", async () => {
+		(mockDb.execute as jest.Mock).mockResolvedValue([{ content: { id: "c1" } }]);
+		const result = await repository.findByUserId("u1", 10, 0);
+		expect(result).toHaveLength(1);
+		expect(result[0].id).toBe("c1");
+	});
+});