added the images/id endpoint and the tests for it

src/app.ts

@@ -14,6 +14,7 @@ app.get("/", (_, res) => {
 });
 
 app.get("/images", imageController.getAllImages);
+app.get("/images/:id", imageController.getImageById);
 app.post("/images", authControler.authorize, imageController.addImage);
 app.post("/login", authControler.login);
 

src/controllers/ImageController.ts

@@ -3,6 +3,23 @@ import imageService from "../services/ImageService";
 import mongoose, { mongo } from "mongoose";
 
 class ImageController {
+  async getImageById(req: Request, res: Response) {
+    try {
+      const image = await imageService.findById(req.params.id);
+      if (image) {
+        res.json({ image });
+      } else {
+        res.status(404).json({ error: "Image not found" });
+      }
+    } catch (error: any) {
+      if (error instanceof mongoose.Error.CastError) {
+        res.status(400).json({ error: "Invalid Id" });
+      } else {
+        res.status(500).json({ error: "Internal Server Error" });
+      }
+    }
+  }
+
   async getAllImages(_: Request, res: Response): Promise<void> {
     try {
       const images = await imageService.findAll();

src/services/ImageService.ts

@@ -1,6 +1,10 @@
 import imageModel, { Image } from "../models/ImageModel";
 
 class ImageService {
+  async findById(id: string) {
+    const image = await imageModel.findOne({ _id: id });
+    return image;
+  }
   async findAll(): Promise<Image[]> {
     const allImages = await imageModel.find();
     return allImages;

tests/app.test.ts

@@ -177,3 +177,26 @@ describe("POST /images works properly", () => {
     expect(res.status).toBe(400);
   });
 });
+
+describe("/images/:id works properly", () => {
+  it("should return 200 for existing ids", async () => {
+    const list = await request(app).get("/images");
+    const id = list.body.images[0]._id;
+    const res = await request(app).get(`/images/${id}`);
+    expect(res.status).toBe(200);
+  });
+
+  it("should return 404 for non-existing ids", async () => {
+    const list = await request(app).get("/images");
+    const id = "000000000000000000000000"; // this was the least posible to exist ID
+    if (!(id in list.body.images)) {
+      const res = await request(app).get(`/images/${id}`);
+      expect(res.status).toBe(404);
+    }
+  });
+
+  it("should return 400 for malformed ids", async () => {
+    const res = await request(app).get("/images/98439384");
+    expect(res.status).toBe(400);
+  });
+});