Improve decoding of JS TypeError.

dart/tests/compiler/dart2js_native/type_error_decode_test.dart

Index: dart/tests/compiler/dart2js_native/type_error_decode_test.dart
diff --git a/dart/tests/compiler/dart2js_native/type_error_decode_test.dart b/dart/tests/compiler/dart2js_native/type_error_decode_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5b70c4dc64089b386a94e8e9478c0715713fdb3a
--- /dev/null
+++ b/dart/tests/compiler/dart2js_native/type_error_decode_test.dart
@@ -0,0 +1,51 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library test.type_error_decode_test;
+
+import 'package:expect/expect.dart';
+
+import 'dart:_js_helper';
+
+class Foo {
+  var field;
+}
+
+isNullError(e, trace) {
+  print('$e\nTrace: $trace');
+  return e is NullError;
+}
+
+isJsNoSuchMethodError(e, trace) {
+  print('$e\nTrace: $trace');
+  return e is JsNoSuchMethodError;
+}
+
+expectThrows(f, check) {
+  try {
+    f();
+  } catch (e, trace) {
+    if (check(e, trace)) {
+      return;
+    }
+    throw 'Unexpected exception: $e\n$trace';
+  }
+  throw 'No exception thrown';
+}
+
+main() {
+  var x = null;
+  var z = new Object();
+  var v = new List(1)[0];
+  var s = "Cannot call method 'foo' of null";
+  var nul = null;
+  var f = new Foo();
+  [].forEach((y) => f.field = nul = s = x = z = v = y);

[ngeoffray, 2013/07/22 09:08:56]

What is this line for? Please add a comment.

[ahe, 2013/07/22 10:45:27]

Done.

+  expectThrows(() => x.fisk(), isNullError);
+  expectThrows(() => v.fisk(), isNullError);
+  expectThrows(() => z.fisk(), isJsNoSuchMethodError);
+  expectThrows(() => s.fisk(), isJsNoSuchMethodError);
+  expectThrows(() => null(), isNullError);
+  expectThrows(() => f.field(), isNullError);
+}