fix http keep-alive test case

Author: dead-horse

package.json

@@ -43,7 +43,9 @@
     "vary": "^1.0.0"
   },
   "devDependencies": {
+    "agentkeepalive": "~2.0.3",
     "babel": "^5.0.0",
+    "freeport": "~1.0.5",
     "istanbul": "^0.4.0",
     "make-lint": "^1.0.1",
     "mocha": "^2.0.1",

test/application.js

@@ -2,8 +2,10 @@
 'use strict';
 
 var stderr = require('test-console').stderr;
+var Agent = require('agentkeepalive');
 var request = require('supertest');
 var statuses = require('statuses');
+var freeport = require('freeport');
 var pedding = require('pedding');
 var assert = require('assert');
 var urllib = require('urllib');
@@ -896,29 +898,47 @@ describe('app.respond', function(){
     })
   })
 
-  it('should not destroy keepalive connection', function(done){
-    done = pedding(2, done);
-    var app = koa();
-    app.use(function *(){
-      var remote = yield urllib.request('http://koajs.com', {
-        streaming: true,
-        headers: {
-          connection: 'keep-alive'
-        }
+  describe('when .body is a http keepalive IncommingMessage', () => {
+    var target;
+    var port;
+    before(function(done){
+      var app = koa();
+      app.use(function *(){
+        this.body = fs.createReadStream(__filename);
       });
-      var res = remote.res;
-      this.body = res;
-      res.once('end', function(){
-        assert.equal(res.readable, false);
-        assert.equal(res.socket.destroyed, false);
-        done();
-      }.bind(this));
-    });
 
-    var server = app.listen();
-    request(server)
-    .head('/')
-    .expect(200, done);
+      freeport(function(err, p){
+        port = p || 12384;
+        target = app.listen(port, done);
+      });
+    })
+
+    after(function(){
+      target.close();
+    })
+
+    it('should not destroy keepalive connection', function(done){
+      done = pedding(2, done);
+      var app = koa();
+      app.use(function *(){
+        var remote = yield urllib.request('http://127.0.0.1:' + port, {
+          streaming: true,
+          agent: new Agent()
+        });
+        var res = remote.res;
+        this.body = res;
+        res.once('end', function(){
+          assert.equal(res.readable, false);
+          assert.equal(res.socket.destroyed, false);
+          done();
+        });
+      });
+
+      var server = app.listen();
+      request(server)
+      .head('/')
+      .expect(200, done);
+    })
   })
 
   describe('when .body is an Object', function(){