An isolated test showing failure of runZonedExperimental on a checked mode exception.

rze_test.dart

import 'package:unittest/unittest.dart';
import 'dart:async';

main() {
  /*
   * In checked mode: Crashes with: 'dart:async/zone.dart': Failed assertion: line 115 pos 12: '! _children.isEmpty' is not true.
   * In unchecked mode: hangs because runZonedExperimental() swallows the completion of the future
   * (due to the fact that an error appears on the Stream, I believe).
   */
  test('Isolated runZonedExperimental failure test.', () {
    var input = new Stream.fromFuture(new Future.error(new ArgumentError('foo')));
    
    var controller = new StreamController<Future>.broadcast(sync: true);
    var sub;

    // Bad type annotation: <String>. Should be <dynamic>.
    var completer = new Completer<String>.sync();
    var outputController = new StreamController();

    // Publish a tracking record for this request (synchronously).
    controller.add(completer.future);

    void done(v, [e]) {
      // Don't complete twice.
      if (completer.isCompleted) {
        return;
      }
      if (v != null) {
        completer.complete(v);
      } else {
        completer.complete(e);
      }
    }
    
    input.first.catchError((e) {
      runZonedExperimental(() {
        outputController.addError(e);
      }, onDone: () => done(null, e));
    });
    
    var output = outputController.stream;
    
    controller.stream.first.then(expectAsync1((onFirstResponse) {
      onFirstResponse.then(expectAsync1((error) {
        expect(error, new isInstanceOf<ArgumentError>());
      }));
    }));
    
    output.listen((_) {
      // Never called.
    }).onError(expectAsync1((error) {
      expect(error, new isInstanceOf<ArgumentError>());
    }));
  });
}