fix(web-server): detach listeners after running

Remove listeners from the global process and the webserver when we're
done. The EmitterWrapper can be used to wrap any EventEmitter and
remembers the listeners that were via the wrappers addListener/on
function. Then the wrapper's removeAllListeners function can be used
to remove the wrapper's listeners, leaving the listeners that were
added directly to the unwrapped emitter attached.

lib/emitter_wrapper.js

@@ -0,0 +1,31 @@
+function EmitterWrapper(emitter) {
+  this.listeners = {};
+  this.emitter = emitter;
+}
+
+EmitterWrapper.prototype.addListener = EmitterWrapper.prototype.on = function (event, listener) {
+  this.emitter.addListener(event, listener);
+
+  if (!this.listeners.hasOwnProperty(event)) {
+    this.listeners[event] = [];
+  }
+
+  this.listeners[event].push(listener);
+
+  return this;
+};
+
+EmitterWrapper.prototype.removeAllListeners = function (event) {
+  var events = event ? [event] : Object.keys(this.listeners);
+  var self = this;
+  events.forEach(function (event) {
+    self.listeners[event].forEach(function (listener) {
+      self.emitter.removeListener(event, listener);
+    });
+    delete self.listeners[event];
+  });
+
+  return this;
+};
+
+module.exports = EmitterWrapper;

lib/server.js

@@ -18,6 +18,8 @@ var EventEmitter = events.EventEmitter;
 var Executor = require('./executor');
 var Browser = require('./browser');
 var BrowserCollection = require('./browser_collection');
+var EmitterWrapper = require('./emitter_wrapper');
+var processWrapper = new EmitterWrapper(process);
 
 var log = logger.create();
 
@@ -198,25 +200,26 @@ var start = function(injector, config, launcher, globalEmitter, preprocess, file
     });
 
     globalEmitter.emitAsync('exit').then(function() {
-      // All systems down, stop the webserver
-      webServer.close(function () {
+      webServer.close(function() {
+        webServer.removeAllListeners();
+        processWrapper.removeAllListeners();
         done(code || 0);
       });
     });
   };
 
 
   try {
-    process.on('SIGINT', disconnectBrowsers);
-    process.on('SIGTERM', disconnectBrowsers);
+    processWrapper.on('SIGINT', disconnectBrowsers);
+    processWrapper.on('SIGTERM', disconnectBrowsers);
   } catch (e) {
     // Windows doesn't support signals yet, so they simply don't get this handling.
     // https://github.com/joyent/node/issues/1553
   }
 
   // Handle all unhandled exceptions, so we don't just exit but
   // disconnect the browsers before exiting.
-  process.on('uncaughtException', function(error) {
+  processWrapper.on('uncaughtException', function (error) {
     log.error(error);
     disconnectBrowsers(1);
   });

test/unit/emitter_wrapper.spec.coffee

@@ -0,0 +1,57 @@
+#==============================================================================
+# lib/emitter_wrapper.js module
+#==============================================================================
+describe 'emitter_wrapper', ->
+  EmitterWrapper = require '../../lib/emitter_wrapper'
+  events = require 'events'
+  EventEmitter = events.EventEmitter
+
+  emitter = null
+  wrapped = null
+  called = false
+
+  beforeEach ->
+    emitter = new EventEmitter()
+    emitter.aMethod = (e) -> called = true
+    emitter.on 'anEvent', emitter.aMethod
+    wrapped = new EmitterWrapper(emitter)
+
+  #===========================================================================
+  # wrapper.addListener
+  #===========================================================================
+  describe 'addListener', ->
+    aListener = (e) -> true
+
+    it 'should add a listener to the wrapped emitter', ->
+      wrapped.addListener 'anEvent', aListener
+      expect(emitter.listeners('anEvent')).to.contain aListener
+
+    it 'returns the wrapped emitter', ->
+      expect(wrapped.addListener 'anEvent', aListener).to.equal wrapped
+
+  #===========================================================================
+  # wrapper.removeAllListeners
+  #===========================================================================
+  describe 'removeAllListeners', ->
+    aListener = (e) -> true
+
+    beforeEach ->
+      wrapped.addListener 'anEvent', aListener
+
+    it 'should remove listeners that were attached via the wrapper', ->
+      wrapped.removeAllListeners()
+      expect(emitter.listeners('anEvent')).not.to.contain aListener
+
+    it 'should not remove listeners that were attached to the original emitter', ->
+      wrapped.removeAllListeners()
+      expect(emitter.listeners('anEvent')).to.contain emitter.aMethod
+
+    it 'should remove only matching listeners when called with an event name', ->
+      anotherListener = (e) -> true
+      wrapped.addListener 'anotherEvent', anotherListener
+      wrapped.removeAllListeners('anEvent')
+      expect(emitter.listeners('anEvent')).not.to.contain aListener
+      expect(emitter.listeners('anotherEvent')).to.contain anotherListener
+
+    it 'returns the wrapped emitter', ->
+      expect(wrapped.addListener 'anEvent', aListener).to.equal wrapped