fix(VmTurnZone): onScheduleMicrotask behaves correctly with orphaned

scheduleMicrotasks.

BREAKING CHANGE:

Zone.defaultOnScheduleMicrotask is now named Zone.onScheduleMircotask

Author: jbdeboer

lib/core/zone.dart

@@ -60,8 +60,6 @@ class VmTurnZone {
   /// an "inner" [Zone], which is a child of the outer [Zone].
   async.Zone _innerZone;
 
-  ZoneScheduleMicrotask defaultOnScheduleMicrotask;
-
   /**
    * Associates with this
    *
@@ -82,6 +80,7 @@ class VmTurnZone {
     onError = _defaultOnError;
     onTurnDone = _defaultOnTurnDone;
     onTurnStart = _defaultOnTurnStart;
+    onScheduleMicrotask = _defaultOnScheduleMicrotask;
   }
 
   List _asyncQueue = [];
@@ -115,11 +114,7 @@ class VmTurnZone {
 
   _onScheduleMicrotask(async.Zone self, async.ZoneDelegate delegate,
                        async.Zone zone, fn()) {
-    if (defaultOnScheduleMicrotask != null) {
-      return defaultOnScheduleMicrotask(fn);
-    }
-
-    _asyncQueue.add(() => delegate.run(zone, fn));
+    onScheduleMicrotask(() => delegate.run(zone, fn));
     if (_runningInTurn == 0 && !_inFinishTurn)  _finishTurn(zone, delegate);
   }
 
@@ -197,6 +192,13 @@ class VmTurnZone {
   ZoneOnTurnDone onTurnDone;
   void _defaultOnTurnDone() => null;
 
+  /**
+   * Called any time a microtask is scheduled. If you override [onScheduleMicrotask], you
+   * are expected to call the function at some point.
+   */
+  ZoneScheduleMicrotask onScheduleMicrotask;
+  void _defaultOnScheduleMicrotask(fn) => _asyncQueue.add(fn);
+
   LongStackTrace _longStacktrace = null;
 
   LongStackTrace _getLongStacktrace(name) {

test/core/zone_spec.dart

@@ -452,7 +452,7 @@ void main() {
           });
           log('onTurnDone(end)');
         };
-        zone.defaultOnScheduleMicrotask = (microTaskFn) {
+        zone.onScheduleMicrotask = (microTaskFn) {
           log('onScheduleMicrotask(begin)');
           microtaskResult = microTaskFn();
           log('onScheduleMicrotask(end)');
@@ -478,7 +478,7 @@ void main() {
           });
           log('onTurnDone(end)');
         };
-        zone.defaultOnScheduleMicrotask = (microTaskFn) {
+        zone.onScheduleMicrotask = (microTaskFn) {
           log('onScheduleMicrotask(begin)');
           microTaskFn();
           log('onScheduleMicrotask(end)');
@@ -500,7 +500,7 @@ void main() {
         zone.onTurnDone = () {
           log('onTurnDone');
         };
-        zone.defaultOnScheduleMicrotask = (microTaskFn) {
+        zone.onScheduleMicrotask = (microTaskFn) {
           log('onScheduleMicrotask(begin)');
           microTaskFn();
           log('onScheduleMicrotask(end)');
@@ -528,7 +528,7 @@ void main() {
         zone.onTurnDone = () {
           log('onTurnDone');
         };
-        zone.defaultOnScheduleMicrotask = (microTaskFn) {
+        zone.onScheduleMicrotask = (microTaskFn) {
           log('onScheduleMicrotask(begin)');
           microTaskFn();
           log('onScheduleMicrotask(end)');
@@ -541,6 +541,36 @@ void main() {
           ' onScheduleMicrotask(end); run; onTurnDone');
       }));
 
+      iit('should execute microtask scheduled outside the turn', (Logger log) {
+        zone = new VmTurnZone();
+
+        var taskToRun = null;
+
+        zone.onTurnDone = () {
+          if (taskToRun != null) taskToRun();
+          taskToRun = null;
+          log('onTurnDone');
+        };
+
+        zone.onScheduleMicrotask = (microTaskFn) {
+          log('onScheduleMicrotask');
+          taskToRun = microTaskFn;
+        };
+
+        var completer;
+        zone.run(() {
+          completer = new Completer();
+          completer.future.then((x) => log('future'));
+          log('first');
+        });
+        completer.complete();
+
+        expect(log).toEqual([
+            'first', 'onTurnDone',
+            'onScheduleMicrotask', 'future', 'onTurnDone'
+        ]);
+      });
+
     });
   });
 }