feat: Add app.handler property

docs/App.md

@@ -13,6 +13,7 @@ const app = medley();
 **Properties:**
 
 + [`.basePath`](#base-path)
++ [`.handler`](#handler)
 + [`.server`](#server)
 
 **Methods:**
@@ -48,6 +49,32 @@ const subSubApp = subApp.createSubApp('/user');
 console.log(subSubApp.basePath); // '/v1/user'
 ```
 
+<a id="handler"></a>
+### `app.handler`
+
+The function passed to `http.createServer()` that handles requests.
+
+This property is `null` until the app has finished [loading](#load).
+
+Helpful when testing with tools like [`supertest`](https://github.com/visionmedia/supertest).
+
+```js
+const request = require('supertest');
+
+describe('GET /', function() {
+  it('responds successfully', async function() {
+    const app = buildAppSomehow();
+
+    await app.load();
+
+    return request(app.handler)
+      .get('/')
+      .expect('content-type', /html/)
+      .expect(200);
+  });
+});
+```
+
 <a id="server"></a>
 ### `app.server`
 

medley.js

@@ -69,9 +69,16 @@ function medley(options) {
     server = http.createServer(requestHandler)
   }
 
+  var loadCallbackQueue = null
+  var loaded = false
+
   const app = {
     server,
 
+    get handler() {
+      return loaded ? requestHandler : null
+    },
+
     createSubApp,
 
     // Decorator methods
@@ -128,9 +135,6 @@ function medley(options) {
 
   var registeringAutoHandlers = false
 
-  var loadCallbackQueue = null
-  var loaded = false
-
   function throwIfAppIsLoaded(msg) {
     if (loaded) {
       throw new Error(msg)

test/app-handler.test.js

@@ -0,0 +1,24 @@
+'use strict'
+
+const t = require('tap')
+const medley = require('..')
+
+t.plan(5)
+
+const app = medley()
+const mockReq = {method: 'GET', url: '/'}
+const mockRes = {}
+
+app.addHook('onRequest', (req, res) => {
+  t.equal(req.stream, mockReq)
+  t.equal(res.stream, mockRes)
+})
+
+t.equal(app.handler, null, 'app.handler is null before app is loaded')
+
+app.load((err) => {
+  t.error(err)
+  t.type(app.handler, 'function')
+
+  app.handler(mockReq, mockRes)
+})