feat: make get user by id use case

src/application/use-cases/get-user-by-id.spec.ts

@@ -0,0 +1,50 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { ResourceNotFoundError } from "@/application/errors/resource-not-found";
+import type { IUserRepository } from "@/domain/repositories/user-repository";
+import { InMemoryUserRepository } from "@/infra/repositories/in-memory/in-memory-user-repository";
+import { GetUserByIdUseCase } from "./get-user-by-id";
+
+describe("GetUserByIdUseCase", () => {
+  let userRepository: IUserRepository;
+  let getUserByIdUseCase: GetUserByIdUseCase;
+
+  beforeEach(() => {
+    userRepository = new InMemoryUserRepository();
+    getUserByIdUseCase = new GetUserByIdUseCase(userRepository);
+  });
+
+  afterEach(() => {
+    vi.resetAllMocks();
+  });
+
+  it("should be able to return the user when found", async () => {
+    const input = { id: "123" };
+
+    userRepository.findById = vi.fn().mockResolvedValue({
+      id: "123",
+    });
+
+    const { user } = await getUserByIdUseCase.execute(input);
+
+    expect(user).toEqual(
+      expect.objectContaining({
+        id: "123",
+      }),
+    );
+    expect(userRepository.findById).toHaveBeenCalledWith("123");
+    expect(userRepository.findById).toHaveBeenCalledTimes(1);
+  });
+
+  it("should throw ResourceNotFoundError when user is not found", async () => {
+    const input = { id: "123" };
+
+    userRepository.findById = vi.fn().mockResolvedValue(null);
+
+    await expect(getUserByIdUseCase.execute(input)).rejects.toThrow(
+      ResourceNotFoundError,
+    );
+    expect(userRepository.findById).toHaveBeenCalledWith("123");
+    expect(userRepository.findById).toHaveBeenCalledOnce();
+  });
+});

src/application/use-cases/get-user-by-id.ts

@@ -0,0 +1,30 @@
+import type { User } from "@/domain/entities/user";
+import type { UseCase } from "@/domain/interfaces/use-case";
+import type { IUserRepository } from "@/domain/repositories/user-repository";
+import { ResourceNotFoundError } from "../errors/resource-not-found";
+
+export type GetUserByIdInput = {
+  id: string;
+};
+
+export type GetUserByIdOutput = {
+  user: User;
+};
+
+export class GetUserByIdUseCase
+  implements UseCase<GetUserByIdInput, GetUserByIdOutput>
+{
+  constructor(private readonly userRepository: IUserRepository) {}
+
+  async execute(input: GetUserByIdInput): Promise<GetUserByIdOutput> {
+    const user = await this.userRepository.findById(input.id);
+
+    if (!user) {
+      throw new ResourceNotFoundError("User");
+    }
+
+    return {
+      user,
+    };
+  }
+}