add socket error-handling. Closes #114

lib/application.js

@@ -97,7 +97,9 @@ app.callback = function(){
 
   return function(req, res, next){
     var ctx = self.createContext(req, res);
-    co.call(ctx, gen)(next || ctx.onerror);
+    next = next || ctx.onerror;
+    ctx.socket.once('error', next);
+    co.call(ctx, gen)(next);
   }
 };
 

lib/context.js

@@ -94,7 +94,7 @@ module.exports = {
     // nothing we can do here other
     // than delegate to the app-level
     // handler and log.
-    if (this.headerSent) {
+    if (this.headerSent || !this.socket.writable) {
       err.headerSent = true;
       this.app.emit('error', err, this);
       return;

test/application.js

@@ -5,6 +5,26 @@ var http = require('http');
 var koa = require('..');
 var fs = require('fs');
 
+describe('app', function(){
+  it('should handle socket errors', function(done){
+    var app = koa();
+
+    app.use(function *(next){
+      // triggers this.socket.writable == false
+      this.socket.emit('error', new Error('boom'));
+    });
+
+    app.on('error', function(err){
+      err.message.should.equal('boom');
+      done();
+    });
+
+    request(app.listen())
+    .get('/')
+    .end(function(){});
+  })
+})
+
 describe('app.use(fn)', function(){
   it('should compose middleware', function(done){
     var app = koa();