Merge pull request #65 from nigrosimone/method-chaining

fix #64

src/router.js

@@ -580,6 +580,7 @@ module.exports = class Router extends EventEmitter {
             }
         }
         this.createRoute('USE', path, this, ...callbacks);
+        return this;
     }
 
     route(path) {

tests/tests/app/app-use-chaining.js

@@ -0,0 +1,24 @@
+// must support app chaining
+
+const express = require("express");
+
+const app = express();
+app.disable('etag');
+
+app.use((req, res, next) => {
+    res.setHeader('a', '1')
+    next();
+}).use((req, res, next) => {
+    res.setHeader('b', '1')
+    next();
+})
+
+app.get('/abc', (req, res) => {
+    res.send('abc');
+});
+
+app.listen(13333, async () => {
+    const output = await fetch('http://localhost:13333/abc');
+    console.log(output.headers.get('etag'));
+    process.exit(0);
+});