Don't propagate synchronous Future.wait errors immediately.

tests/lib/async/future_test.dart

Index: tests/lib/async/future_test.dart
diff --git a/tests/lib/async/future_test.dart b/tests/lib/async/future_test.dart
index 71c509b6fd3973e7790df4418d8b1e55dd7bcb72..ef879670847ce71cf5edc1a73382c5ad37e760a9 100644
--- a/tests/lib/async/future_test.dart
+++ b/tests/lib/async/future_test.dart
@@ -879,7 +879,6 @@ void testWaitCleanUpError() {
 void testWaitSyncError() {
   var cms = const Duration(milliseconds: 100);
   var cleanups = new List.filled(3, false);
-  var uncaughts = new List.filled(3, false);
   asyncStart();
   asyncStart();
   runZoned(() {
@@ -896,6 +895,40 @@ void testWaitSyncError() {
   });
 }
 
+void testWaitSyncError2() {
+  asyncStart();
+  Future.wait([null]).catchError((e, st) {
+    // Makes sure that the `catchError` is invoked.
+    // Regression test: an earlier version of `Future.wait` would propagate
+    // the error too soon for the code to install an error handler.
+    // `testWaitSyncError` didn't show this problem, because the `runZoned`
+    // was already installed.
+    asyncEnd();
+  });
+}
+
+void testWaitSyncError3() {

[Lasse Reichstein Nielsen, 2016/09/06 09:53:27]

Add comment saying what you are testing: That zone.errorCallback intercepts the
synchronous error when it becomes an async error.

[floitsch, 2016/09/06 09:57:15]

Done.

+  var caughtError;
+  var count = 0;
+
+  AsyncError errorCallback(
+      Zone self, ZoneDelegate parent, Zone zone, Object error,
+      StackTrace stackTrace) {
+    Expect.equals(0, count);
+    count++;
+    caughtError = error;
+    return parent.errorCallback(zone, error, stackTrace);
+  }
+
+  asyncStart();
+  runZoned(() {
+    Future.wait([null]).catchError((e, st) {
+      Expect.isNotNull(caughtError);

[Lasse Reichstein Nielsen, 2016/09/06 09:53:27]

Check that caughtError is identical to e.

[floitsch, 2016/09/06 09:57:16]

Done.

+      asyncEnd();
+    });
+  }, zoneSpecification: new ZoneSpecification(errorCallback: errorCallback));
+}
+
 void testBadFuture() {
   var bad = new BadFuture();
   // Completing with bad future (then call throws) puts error in result.
@@ -1096,6 +1129,8 @@ main() {
   testWaitCleanUp();
   testWaitCleanUpError();
   testWaitSyncError();
+  testWaitSyncError2();
+  testWaitSyncError3();
 
   testBadFuture();