[test] Add core `test-http-client-abort` test

Modifications:

  * make client connect to `PROXY_PORT` instead of `PORT`

As off a95cf9bd63, this test doesn't hang.

test/core/simple/test-http-client-abort.js

+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var http = require('http');
+
+var clientAborts = 0;
+
+var server = http.Server(function(req, res) {
+  console.log('Got connection');
+  res.writeHead(200);
+  res.write('Working on it...');
+
+  // I would expect an error event from req or res that the client aborted
+  // before completing the HTTP request / response cycle, or maybe a new
+  // event like "aborted" or something.
+  req.on('aborted', function() {
+    clientAborts++;
+    console.log('Got abort ' + clientAborts);
+    if (clientAborts === N) {
+      console.log('All aborts detected, you win.');
+      server.close();
+    }
+  });
+
+  // since there is already clientError, maybe that would be appropriate,
+  // since "error" is magical
+  req.on('clientError', function() {
+    console.log('Got clientError');
+  });
+});
+
+var responses = 0;
+var N = http.Agent.defaultMaxSockets - 1;
+var requests = [];
+
+server.listen(common.PORT, function() {
+  console.log('Server listening.');
+
+  for (var i = 0; i < N; i++) {
+    console.log('Making client ' + i);
+    var options = { port: common.PROXY_PORT, path: '/?id=' + i };
+    var req = http.get(options, function(res) {
+      console.log('Client response code ' + res.statusCode);
+
+      if (++responses == N) {
+        console.log('All clients connected, destroying.');
+        requests.forEach(function(outReq) {
+          console.log('abort');
+          outReq.abort();
+        });
+      }
+    });
+
+    requests.push(req);
+  }
+});
+
+process.on('exit', function() {
+  assert.equal(N, clientAborts);
+});