Added unit tests via supertest, mocha

test/app.test.js

@@ -0,0 +1,10 @@
+const request = require('supertest');
+const { expect } = require('chai');
+const app = require('../src/app');
+
+describe('GET /', () => {
+  it('should run the app server', async () => {
+    const res = await request(app).get('/');
+    expect(res.status).to.equal(200);
+  });
+});