fix test

src/router.js

@@ -68,7 +68,7 @@ module.exports = class Router extends EventEmitter {
 
         for(let method of methods) {
             this[method] = (path, ...callbacks) => {
-                this.createRoute(method.toUpperCase(), path, this, ...callbacks);
+                return this.createRoute(method.toUpperCase(), path, this, ...callbacks);
             };
         };
     }

tests/tests/app/app-chaining.js

@@ -0,0 +1,25 @@
+// must support app chaining
+
+const express = require("express");
+
+const app = express();
+
+app.use((req, res, next) => {
+    res.setHeader('a', '1')
+    next();
+}).use((req, res, next) => {
+    res.setHeader('b', '1')
+    next();
+}).post('/abc', (req, res) => {
+    res.send('abc');
+}).get('/def', (req, res) => {
+    res.send('def');
+});
+
+app.listen(13333, async () => {
+    const output = await fetch('http://localhost:13333/abc', { method: 'POST' });
+    console.log(output.headers.get('etag'), await output.text());
+    const output2 = await fetch('http://localhost:13333/def');
+    console.log(output2.headers.get('etag'), await output2.text());
+    process.exit(0);
+});