Don't try to infer that the current isolate is executing an event.

tests/isolate/ping_test.dart

Index: tests/isolate/ping_test.dart
diff --git a/tests/isolate/ping_test.dart b/tests/isolate/ping_test.dart
index 018eb0d0ca070e178aa5a4571fd19ca6f7a09070..48b1ec5b95532e4d5565e02aa3699b38e7f340ea 100644
--- a/tests/isolate/ping_test.dart
+++ b/tests/isolate/ping_test.dart
@@ -27,19 +27,22 @@ void main(){
         result.add(v);
         if (v == 0) {
           Expect.listEquals(["alive", "control", "event"],
-                            result.where((x) => x is String).toList());
+                            result.where((x) => x is String).toList(),
+                            "control events");
           Expect.listEquals([4, 3, 2, 1, 0],
-                            result.where((x) => x is int).toList());
-          Expect.isTrue(result.indexOf("alive") < result.indexOf(3));
-          Expect.isTrue(result.indexOf("control") < result.indexOf(2));
+                            result.where((x) => x is int).toList(),
+                            "data events");
+          Expect.isTrue(result.indexOf("alive") < result.indexOf(3),
+                        "alive index < 3");
+          Expect.isTrue(result.indexOf("control") < result.indexOf(2),
+                        "control index < 2");
           int eventIndex = result.indexOf("event");
-          Expect.isTrue(eventIndex > result.indexOf(2));
-          Expect.isTrue(eventIndex < result.indexOf(1));
+          Expect.isTrue(eventIndex > result.indexOf(2), "event index > 2");
+          Expect.isTrue(eventIndex < result.indexOf(1), "event index < 1");
           reply.close();
           asyncEnd();
         }
       };
-      echoPort.send(4);
       SendPort createPingPort(message) {
         var pingPort = new RawReceivePort();
         pingPort.handler = (_) {
@@ -48,6 +51,7 @@ void main(){
         };
         return pingPort.sendPort;
       }
+      echoPort.send(4);
       isolate.ping(createPingPort("alive"), Isolate.IMMEDIATE);
       echoPort.send(3);
       isolate.ping(createPingPort("control"), Isolate.BEFORE_NEXT_EVENT);