test: add cluster EADDRINUSE test

Check that having a worker bind to a port that's already taken doesn't
leave the master process in a confused state. Releasing the port and
trying again should Just Work[TM].

test/simple/test-cluster-eaddrinuse.js

@@ -0,0 +1,63 @@
+// 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.
+
+// Check that having a worker bind to a port that's already taken doesn't
+// leave the master process in a confused state. Releasing the port and
+// trying again should Just Work[TM].
+
+var common = require('../common');
+var assert = require('assert');
+var cluster = require('cluster');
+var fork = require('child_process').fork;
+var net = require('net');
+
+var id = '' + process.argv[2];
+
+if (id === 'undefined') {
+  var server = net.createServer(assert.fail);
+  server.listen(common.PORT, function() {
+    var worker = fork(__filename, ['worker']);
+    worker.on('message', function(msg) {
+      if (msg !== 'stop-listening') return;
+      server.close(function() {
+        worker.send('stopped-listening');
+      });
+    });
+  });
+}
+else if (id === 'worker') {
+  var server = net.createServer(assert.fail);
+  server.listen(common.PORT, assert.fail);
+  server.on('error', common.mustCall(function(e) {
+    assert(e.code, 'EADDRINUSE');
+    process.send('stop-listening');
+    process.once('message', function(msg) {
+      if (msg !== 'stopped-listening') return;
+      server = net.createServer(assert.fail);
+      server.listen(common.PORT, common.mustCall(function() {
+        server.close();
+      }));
+    });
+  }));
+}
+else {
+  assert(0);  // Bad argument.
+}