Issue: Split up index and app for testing with Jest (#5)

server/src/app.ts

+import express, { Application } from 'express';
+import routes from "./routes/routes";
+import bodyParser from 'body-parser';
+import cors from 'cors';
+import mysql from 'mysql2';
+// Boot express
+const app: Application = express();
+
+app.use(cors());
+// Configuring body parser middleware
+app.use(bodyParser.urlencoded({ extended: false }));
+app.use(bodyParser.json());
+
+// Configuring json response
+app.set("json spaces", 2);
+
+app.use("/api", routes);
+
+export default app;
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server/src/index.ts

-import bodyParser from 'body-parser';
-import cors from 'cors';
-import express from 'express';
-import routes from './routes/routes';
-import mysql from 'mysql2';
+import app from './app';
 
 // REST API config
-const app = express();
 const port = 3000;
 
-app.use(cors());
-// Configuring body parser middleware
-app.use(bodyParser.urlencoded({ extended: false }));
-app.use(bodyParser.json());
-
-// Configuring json response
-app.set("json spaces", 2);
-
-app.use("/api", routes);
-
 app.listen(port, () => {
 	console.log(`Listening on port ${port}!`)
 });
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