Add missing null-tests to async error functions.

Also treat null errors comming out of Zone.errorCallback as
NullThrownError.

This should prevent, as was always the intention, any async error
from having a null value.
This is important for async/await syntax, where the distinction
between sync and async errors is removed.

(For Dart 2.0, we could just make null throwable).

R=sgjesse@google.com

Review URL: https://codereview.chromium.org//598993002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@40673 260f80e4-7a28-3924-810f-c04153c831b5

sdk/lib/async/broadcast_stream_controller.dart

@@ -238,10 +238,11 @@ abstract class _BroadcastStreamController<T>
   }
 
   void addError(Object error, [StackTrace stackTrace]) {
+    error = _nonNullError(error);
     if (!_mayAddEvent) throw _addEventError();
     AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
     if (replacement != null) {
-      error = replacement.error;
+      error = _nonNullError(replacement.error);
       stackTrace = replacement.stackTrace;
     }
     _sendError(error, stackTrace);

sdk/lib/async/future.dart

@@ -187,13 +187,16 @@ abstract class Future<T> {
   /**
    * A future that completes with an error in the next event-loop iteration.
    *
-   * Use [Completer] to create a Future and complete it later.
+   * If [error] is `null`, it is replaced by a [NullThrownError].
+   *
+   * Use [Completer] to create a future and complete it later.
    */
   factory Future.error(Object error, [StackTrace stackTrace]) {
+    error = _nonNullError(error);
     if (!identical(Zone.current, _ROOT_ZONE)) {
       AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
       if (replacement != null) {
-        error = replacement.error;
+        error = _nonNullError(replacement.error);
         stackTrace = replacement.stackTrace;
       }
     }
@@ -663,10 +666,13 @@ abstract class Completer<T> {
 // for error replacement first.
 void _completeWithErrorCallback(_Future result, error, stackTrace) {
   AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
-  if (replacement == null) {
-    result._completeError(error, stackTrace);
-  } else {
-    result._completeError(replacement.error, replacement.stackTrace);
+  if (replacement != null) {
+    error = _nonNullError(replacement.error);
+    stackTrace = replacement.stackTrace;
   }
+  result._completeError(error, stackTrace);
 }
 
+/** Helper function that converts `null` to a [NullThrownError]. */
+Object _nonNullError(Object error) =>
+  (error != null) ? error : new NullThrownError();

sdk/lib/async/future_impl.dart

@@ -17,11 +17,11 @@ abstract class _Completer<T> implements Completer<T> {
   void complete([value]);
 
   void completeError(Object error, [StackTrace stackTrace]) {
-    if (error == null) throw new ArgumentError("Error must not be null");
+    error = _nonNullError(error);
     if (!future._mayComplete) throw new StateError("Future already completed");
     AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
     if (replacement != null) {
-      error = replacement.error;
+      error = _nonNullError(replacement.error);
       stackTrace = replacement.stackTrace;
     }
     _completeError(error, stackTrace);
@@ -47,7 +47,6 @@ class _AsyncCompleter<T> extends _Completer<T> {
 }
 
 class _SyncCompleter<T> extends _Completer<T> {
-
   void complete([value]) {
     if (!future._mayComplete) throw new StateError("Future already completed");
     future._complete(value);

sdk/lib/async/stream.dart

@@ -1382,7 +1382,7 @@ abstract class EventSink<T> implements Sink<T> {
   void add(T event);
   /** Send an async error to a stream. */
   void addError(errorEvent, [StackTrace stackTrace]);
-  /** Send a done event to a stream.*/
+  /** Send a done event to a stream. */
   void close();
 }
 

sdk/lib/async/stream_controller.dart

@@ -168,6 +168,8 @@ abstract class StreamController<T> implements StreamSink<T> {
   /**
    * Send or enqueue an error event.
    *
+   * If [error] is `null`, it is replaced by a [NullThrownError].
+   *
    * Also allows an objection stack trace object, on top of what [EventSink]
    * allows.
    */
@@ -414,10 +416,11 @@ abstract class _StreamController<T> implements StreamController<T>,
    * Send or enqueue an error event.
    */
   void addError(Object error, [StackTrace stackTrace]) {
+    error = _nonNullError(error);
     if (!_mayAddEvent) throw _badEventState();
     AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
     if (replacement != null) {
-      error = replacement.error;
+      error = _nonNullError(replacement.error);
       stackTrace = replacement.stackTrace;
     }
     _addError(error, stackTrace);

sdk/lib/async/stream_pipe.dart

@@ -15,7 +15,9 @@ _runUserCode(userCode(),
     if (replacement == null) {
       onError(e, s);
     } else {
-      onError(replacement.error, replacement.stackTrace);
+      var error = _nonNullError(replacement.error);
+      var stackTrace = replacement.stackTrace;
+      onError(error, stackTrace);
     }
   }
 }
@@ -39,7 +41,7 @@ void _cancelAndErrorWithReplacement(StreamSubscription subscription,
                                     error, StackTrace stackTrace) {
   AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
   if (replacement != null) {
-    error = replacement.error;
+    error = _nonNullError(replacement.error);
     stackTrace = replacement.stackTrace;
   }
   _cancelAndError(subscription, future, error, stackTrace);
@@ -187,11 +189,11 @@ typedef bool _Predicate<T>(T value);
 
 void _addErrorWithReplacement(_EventSink sink, error, stackTrace) {
   AsyncError replacement = Zone.current.errorCallback(error, stackTrace);
-  if (replacement == null) {
-    sink._addError(error, stackTrace);
-  } else {
-    sink._addError(replacement.error, replacement.stackTrace);
+  if (replacement != null) {
+    error = _nonNullError(replacement.error);
+    stackTrace = replacement.stackTrace;
   }
+  sink._addError(error, stackTrace);
 }
 
 

sdk/lib/async/zone.dart

@@ -36,12 +36,13 @@ typedef Zone ForkHandler(Zone self, ZoneDelegate parent, Zone zone,
                          ZoneSpecification specification,
                          Map zoneValues);
 
-/// Pair of error and stack trace. Returned by [Zone.errorCallback].
+/** Pair of error and stack trace. Returned by [Zone.errorCallback]. */
 class AsyncError implements Error {
   final error;
   final StackTrace stackTrace;
 
   AsyncError(this.error, this.stackTrace);
+
   String toString() => error.toString();
 }
 
@@ -254,10 +255,10 @@ abstract class Zone {
   // Private constructor so that it is not possible instantiate a Zone class.
   Zone._();
 
-  /// The root zone that is implicitly created.
+  /** The root zone that is implicitly created. */
   static const Zone ROOT = _ROOT_ZONE;
 
-  /// The currently running zone.
+  /** The currently running zone. */
   static Zone _current = _ROOT_ZONE;
 
   static Zone get current => _current;

tests/co19/co19-co19.status

@@ -17,7 +17,7 @@ LibTest/isolate/IsolateStream/contains_A02_t01: Fail # co19 issue 668
 LibTest/typed_data/ByteData/buffer_A01_t01: Fail # co19 r736 bug - sent comment.
 
 # TODO(terry) re-enable the below CSS tests when Chrome 38 and (Dartium 38) are ready issue 21075
-LayoutTests/fast/css/getComputedStyle/computed-style-font_t01: Skip 
+LayoutTests/fast/css/getComputedStyle/computed-style-font_t01: Skip
 LayoutTests/fast/css/font-shorthand-from-longhands_t01: Skip
 
 Language/07_Classes/6_Constructors/1_Generative_Constructors_A01_t06: Fail, Pass, OK # co19 issue 695
@@ -29,6 +29,8 @@ WebPlatformTest/shadow-dom/elements-and-dom-objects/shadowroot-object/shadowroot
 [ $compiler != dartanalyzer && $compiler != dart2analyzer ]
 # Tests that fail on every runtime, but not on the analyzer.
 
+LibTest/async/Future/Future.error_A01_t01: RuntimeError # co19 issue 712
+LibTest/async/Completer/completeError_A02_t01: RuntimeError # co19 issue 712
 LibTest/isolate/ReceivePort/asBroadcastStream_A02_t01: Fail # co19 issue 687
 LibTest/async/Stream/asBroadcastStream_A02_t01: Fail # co19 issue 687
 

tests/lib/async/future_test.dart

@@ -677,8 +677,13 @@ void testCompleteErrorWithCustomFuture() {
 }
 
 void testCompleteErrorWithNull() {
+  asyncStart();
   final completer = new Completer<int>();
-  Expect.throws(() => completer.completeError(null));
+  completer.future.catchError((e) {
+    Expect.isTrue(e is NullThrownError);
+    asyncEnd();
+  });
+  completer.completeError(null);
 }
 
 void testChainedFutureValue() {

tests/lib/async/stream_controller_async_test.dart

@@ -380,7 +380,7 @@ testRethrow() {
       Stream s = streamErrorTransform(c.stream, (e) { throw error; });
       s.listen((_) { Expect.fail("unexpected value"); }, onError: expectAsync(
           (e) { Expect.identical(error, e); }));
-      c.addError(null);
+      c.addError("SOME ERROR");
       c.close();
     });
   }