multicast: don't reconnect once subject is stopped

A stopped subject shouldn't forward any more events, so using it to
subscribe again is pointless at best and a cause of undesirable side
effects at worst.

Fixes #1112

Author: rhendric

src/core/linq/connectableobservable.js

@@ -55,6 +55,9 @@
 
     ConnectableObservable.prototype.connect = function () {
       if (!this._connection) {
+        if (this._subject.isStopped) {
+          return disposableEmpty;
+        }
         var subscription = this._source.subscribe(this._subject);
         this._connection = new ConnectDisposable(this, subscription);
       }

tests/observable/multicast.js

@@ -1,7 +1,7 @@
 (function () {
   'use strict';
   /* jshint undef: true, unused: true */
-  /* globals QUnit, test, Rx */
+  /* globals QUnit, test, Rx, equal */
 
   QUnit.module('multicast');
 
@@ -478,4 +478,52 @@
       subscribe(200, 390));
   });
 
+  // adapted from issue Reactive-Extensions/RxJS#1112
+  test("multicast should not reconnect when stopped", function () {
+    var scheduler = new TestScheduler();
+
+    var results = scheduler.createObserver();
+
+    var calls = 0;
+
+    function request(v) {
+      calls++;
+      return v * 2;
+    }
+
+    var xs = scheduler.createColdObservable(
+      onNext(1, 1),
+      onNext(2, 2),
+      onNext(3, 3),
+      onCompleted(4));
+
+    var c, s;
+
+    scheduler.scheduleAbsolute(null, 300, function () {
+      c = new Rx.AnonymousObservable(function (o) {
+        return xs.subscribe(
+          function (x) { o.onNext(request(x)); },
+          function (e) { o.onError(e); },
+          function () { o.onCompleted(); });
+      }).multicast(new Subject());
+      c.subscribe(results);
+      s = c.connect();
+    });
+
+    scheduler.scheduleAbsolute(null, 400, function () {
+      s.dispose();
+      c.connect();
+    });
+
+    scheduler.start();
+
+    equal(calls, 3);
+
+    results.messages.assertEqual(
+      onNext(301, 2),
+      onNext(302, 4),
+      onNext(303, 6),
+      onCompleted(304));
+  });
+
 }());