add routes

Author: wechuli

__tests__/main.test.js

@@ -0,0 +1,10 @@
+const request = require("supertest");
+const app = require("../src/app");
+
+describe("GET /", () => {
+  it("responds with Hello World!", async () => {
+    const response = await request(app).get("/");
+    expect(response.statusCode).toBe(200);
+    expect(response.text).toBe("Hello World!");
+  });
+});