Issue 6855 - Release all references to Subscription object once removed

test/filterStorage.js

Index: test/filterStorage.js
===================================================================
--- a/test/filterStorage.js
+++ b/test/filterStorage.js
@@ -34,21 +34,28 @@
     {FilterNotifier} = sandboxedRequire("../lib/filterNotifier"),
     {FilterStorage} = sandboxedRequire("../lib/filterStorage"),
     {Subscription} = sandboxedRequire("../lib/subscriptionClasses")
   );
 
   callback();
 };
 
-function compareSubscriptionList(test, testMessage, list)
+function compareSubscriptionList(test, testMessage, list,
+                                 knownSubscriptions = null)
 {
   let result = FilterStorage.subscriptions.map(subscription => subscription.url);
   let expected = list.map(subscription => subscription.url);
   test.deepEqual(result, expected, testMessage);
+
+  if (knownSubscriptions)
+  {
+    test.deepEqual([...Subscription.knownSubscriptions.values()],
+                   knownSubscriptions, testMessage);
+  }
 }
 
 function compareFiltersList(test, testMessage, list)
 {
   let result = FilterStorage.subscriptions.map(
     subscription => subscription.filters.map(
       filter => filter.text));
   test.deepEqual(result, list, testMessage);
@@ -113,34 +120,44 @@
   let changes = [];
   function listener(action, subscription)
   {
     if (action.indexOf("subscription.") == 0)
       changes.push(action + " " + subscription.url);
   }
   FilterNotifier.addListener(listener);
 
-  compareSubscriptionList(test, "Initial state", [subscription1, subscription2]);
+  compareSubscriptionList(test, "Initial state", [subscription1, subscription2],
+                          [subscription1, subscription2]);
   test.deepEqual(changes, [], "Received changes");
 
   changes = [];
   FilterStorage.removeSubscription(subscription1);
-  compareSubscriptionList(test, "Removing first subscription", [subscription2]);
+  compareSubscriptionList(test, "Removing first subscription", [subscription2],
+                          [subscription2]);
   test.deepEqual(changes, ["subscription.removed http://test1/"], "Received changes");
 
   changes = [];
   FilterStorage.removeSubscription(subscription1);
-  compareSubscriptionList(test, "Removing already removed subscription", [subscription2]);
+  compareSubscriptionList(test, "Removing already removed subscription", [subscription2],
+                          [subscription2]);
   test.deepEqual(changes, [], "Received changes");
 
   changes = [];
   FilterStorage.removeSubscription(subscription2);
-  compareSubscriptionList(test, "Removing remaining subscription", []);
+  compareSubscriptionList(test, "Removing remaining subscription", [], []);
   test.deepEqual(changes, ["subscription.removed http://test2/"], "Received changes");
 
+  // Compare references to make sure that a new object is created for the same
+  // subscription URL.
+  test.notEqual(Subscription.fromURL(subscription2.url), subscription2,
+                "Subscription forgotten");
+
+  // Adding a removed Subscription object back still works but is not
+  // recommended.
   FilterStorage.addSubscription(subscription1);
   compareSubscriptionList(test, "Add", [subscription1]);
 
   changes = [];
   FilterStorage.removeSubscription(subscription1);
   compareSubscriptionList(test, "Re-removing previously added subscription", []);
   test.deepEqual(changes, ["subscription.removed http://test1/"], "Received changes");
 
@@ -461,16 +478,22 @@
   compareFilterSubscriptions(test, "filter3 subscriptions after adding http://test1/", filter3, []);
 
   FilterStorage.addSubscription(subscription2);
 
   compareFilterSubscriptions(test, "filter1 subscriptions after adding http://test2/", filter1, [subscription1]);
   compareFilterSubscriptions(test, "filter2 subscriptions after adding http://test2/", filter2, [subscription1, subscription2]);
   compareFilterSubscriptions(test, "filter3 subscriptions after adding http://test2/", filter3, [subscription2]);
 
+  // Test duplicate subscription entries, which can occur when a subscription
+  // is loaded from disk and contains the same filter more than once.
+  filter1.subscriptions.push(subscription1);
+  compareFilterSubscriptions(test, "filter1 subscriptions after duplicating http://test1/",
+                             filter1, [subscription1, subscription1]);
+
   FilterStorage.removeSubscription(subscription1);
 
   compareFilterSubscriptions(test, "filter1 subscriptions after removing http://test1/", filter1, []);
   compareFilterSubscriptions(test, "filter2 subscriptions after removing http://test1/", filter2, [subscription2]);
   compareFilterSubscriptions(test, "filter3 subscriptions after removing http://test1/", filter3, [subscription2]);
 
   FilterStorage.updateSubscriptionFilters(subscription3, [filter3]);