valid and invalid URL of the url-shortener.service.spec.ts

src/app.controller.spec.ts

@@ -1,22 +0,0 @@
-import { Test, TestingModule } from '@nestjs/testing';
-import { AppController } from './app.controller';
-import { AppService } from './app.service';
-
-describe('AppController', () => {
-  let appController: AppController;
-
-  beforeEach(async () => {
-    const app: TestingModule = await Test.createTestingModule({
-      controllers: [AppController],
-      providers: [AppService],
-    }).compile();
-
-    appController = app.get<AppController>(AppController);
-  });
-
-  describe('root', () => {
-    it('should return "Hello World!"', () => {
-      expect(appController.getHello()).toBe('Hello World!');
-    });
-  });
-});

src/dns/dns.service.ts

@@ -7,6 +7,7 @@ export class DnsService {
   private lookup = util.promisify(dns.lookup);
 
   async isValidUrl(url: string): Promise<boolean> {
+    console.log(url)
     try {
       const hostname = new URL(url).hostname;
       await this.lookup(hostname);

src/url-shortener/url-shortener.controller.spec.ts

@@ -1,18 +0,0 @@
-import { Test, TestingModule } from '@nestjs/testing';
-import { UrlShortenerController } from './url-shortener.controller';
-
-describe('UrlShortenerController', () => {
-  let controller: UrlShortenerController;
-
-  beforeEach(async () => {
-    const module: TestingModule = await Test.createTestingModule({
-      controllers: [UrlShortenerController],
-    }).compile();
-
-    controller = module.get<UrlShortenerController>(UrlShortenerController);
-  });
-
-  it('should be defined', () => {
-    expect(controller).toBeDefined();
-  });
-});

src/url-shortener/url-shortener.service.spec.ts

@@ -1,18 +1,40 @@
 import { Test, TestingModule } from '@nestjs/testing';
 import { UrlShortenerService } from './url-shortener.service';
+import { DnsService } from '../dns/dns.service';
 
 describe('UrlShortenerService', () => {
   let service: UrlShortenerService;
+  let dnsService: DnsService;
 
   beforeEach(async () => {
     const module: TestingModule = await Test.createTestingModule({
-      providers: [UrlShortenerService],
+      providers: [
+        UrlShortenerService,
+        { provide: DnsService, useValue: { isValidUrl: jest.fn().mockResolvedValue(true) } },
+      ],
     }).compile();
 
     service = module.get<UrlShortenerService>(UrlShortenerService);
+    dnsService = module.get<DnsService>(DnsService);
   });
 
   it('should be defined', () => {
     expect(service).toBeDefined();
   });
+
+  it('should generate and retrieve a short URL', async () => {
+    jest.spyOn(dnsService, 'isValidUrl').mockResolvedValue(true);
+    const url = 'https://example.com';
+    const shortUrl = await service.generateShortUrl(url);
+    expect(shortUrl).toBeDefined();
+    expect(await service.getOriginalUrl(shortUrl)).toBe(url);
+  });
+
+  it('should throw an error for an invalid URL', async () => {
+    jest.spyOn(dnsService, 'isValidUrl').mockResolvedValue(false);
+    const url = 'http://invalid-url';
+  
+    await expect(service.generateShortUrl(url)).rejects.toThrow('URL is invalid');
+  });
+
 });