Update custom-server-micro example to latest version (vercel#3594)

Author: sergiodxa

examples/custom-server-micro/package.json

@@ -1,17 +1,18 @@
 {
+  "main": "server.js",
   "scripts": {
-    "dev": "node server.js",
+    "dev": "micro-dev --watch server.js",
     "build": "next build",
-    "start": "NODE_ENV=production node server.js"
+    "start": "NODE_ENV=production micro"
   },
   "dependencies": {
-    "micro": "^8.0.1",
+    "micro": "^9.1.0",
     "micro-route": "^2.4.0",
     "next": "latest",
     "react": "^16.1.1",
     "react-dom": "^16.1.1"
   },
   "devDependencies": {
-    "micro-dev": "^1.1.2"
+    "micro-dev": "^2.2.0"
   }
 }

examples/custom-server-micro/server.js

@@ -1,29 +1,31 @@
-const micro = require('micro')
-const match = require('micro-route/match')
 const { parse } = require('url')
+const match = require('micro-route/match')
 const next = require('next')
 
-const port = parseInt(process.env.PORT, 10) || 3000
 const dev = process.env.NODE_ENV !== 'production'
+
 const app = next({ dev })
 const handle = app.getRequestHandler()
 
-const server = micro(async (req, res) => {
+const isA = req => match(req, '/a')
+const isB = req => match(req, '/b')
+
+async function main (req, res) {
   const parsedUrl = parse(req.url, true)
   const { query } = parsedUrl
 
-  if (match(req, '/a')) {
+  if (isA(req)) {
     return app.render(req, res, '/b', query)
-  } else if (match(req, '/b')) {
+  } else if (isB(req)) {
     return app.render(req, res, '/a', query)
   }
 
   return handle(req, res, parsedUrl)
-})
-
-app.prepare().then(() => {
-  server.listen(port, err => {
-    if (err) throw err
-    console.log(`> Ready on http://localhost:${port}`)
-  })
-})
+}
+
+async function setup (handler) {
+  await app.prepare()
+  return handler
+}
+
+module.exports = setup(main)