this.writable to check if the socket is writable

because node sucks haha

lib/application.js

@@ -152,7 +152,7 @@ function *respond(next){
   if (false === this.respond) return;
 
   var res = this.res;
-  if (res.headersSent || !res.socket.writable) return;
+  if (res.headersSent || !this.writable) return;
 
   var body = this.body;
   var status = this.status = this.status || 404;

lib/context.js

@@ -106,7 +106,7 @@ var proto = module.exports = {
     // nothing we can do here other
     // than delegate to the app-level
     // handler and log.
-    if (this.headerSent || !this.socket.writable) {
+    if (this.headerSent || !this.writable) {
       err.headerSent = true;
       this.app.emit('error', err, this);
       return;
@@ -153,6 +153,7 @@ delegate(proto, 'response')
   .access('type')
   .access('charset')
   .getter('headerSent')
+  .getter('writable')
   .setter('lastModified')
   .setter('etag');
 

lib/response.js

@@ -434,6 +434,21 @@ module.exports = {
     this.set(field, list.join(', '));
   },
 
+  /**
+   * Checks if the request is writable.
+   * Tests for the existence of the socket
+   * as node sometimes does not set it.
+   *
+   * @return {Boolean}
+   * @api private
+   */
+
+  get writable() {
+    var socket = this.res.socket;
+    if (!socket) return false;
+    return socket.writable;
+  },
+
   /**
    * Inspect implementation.
    *

test/context/writable.js

@@ -0,0 +1,10 @@
+
+var context = require('../context');
+
+describe('ctx.writable', function(){
+  it('should not crash when the socket does not exist', function(){
+    var ctx = context();
+    ctx.socket = null;
+    ctx.writable.should.equal(false);
+  })
+})