Migrated test block 168 to Dart 2.0.

tests/lib_2/async/first_regression_test.dart

 // Copyright (c) 2012, 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.
 
 // Regression test for http://dartbug.com/7964
 
 library first_regression_test;
 
 import 'dart:async';
-import 'package:unittest/unittest.dart';
+import 'package:test/test.dart';

[bkonyi, 2017/08/14 23:33:14]

There seems to be a failure somewhere inside this package along the lines of
this:

[error] Undefined class 'A'. (package:test/src/frontend/expect_async.dart, line
28, col 16)
[error] Undefined class 'A'. (package:test/src/frontend/expect_async.dart, line
29, col 16)
[error] Undefined class 'B'. (package:test/src/frontend/expect_async.dart, line
29, col 21)
[error] Undefined class 'A'. (package:test/src/frontend/expect_async.dart, line
30, col 16)
[error] Undefined class 'B'. (package:test/src/frontend/expect_async.dart, line
30, col 21)
[error] Undefined class 'C'. (package:test/src/frontend/expect_async.dart, line
30, col 26)
[error] Undefined class 'A'. (package:test/src/frontend/expect_async.dart, line
31, col 16)
[error] Undefined class 'B'. (package:test/src/frontend/expect_async.dart, line
31, col 21)
[error] Undefined class 'C'. (package:test/src/frontend/expect_async.dart, line
31, col 26)
[error] Undefined class 'D'. (package:test/src/frontend/expect_async.dart, line
31, col 31)
[error] Undefined class 'A'. (package:test/src/frontend/expect_async.dart, line
32, col 16)
[error] Undefined class 'B'. (package:test/src/frontend/expect_async.dart, line
32, col 21)
[error] Undefined class 'C'. (package:test/src/frontend/expect_async.dart, line
32, col 26)
[error] Undefined class 'D'. (package:test/src/frontend/expect_async.dart, line
32, col 31)
[error] Undefined class 'E'. (package:test/src/frontend/expect_async.dart, line
32, col 36)
[error] Undefined class 'A'. (package:test/src/frontend/expect_async.dart, line
33, col 16)
[error] Undefined class 'B'. (package:test/src/frontend/expect_async.dart, line
33, col 21)
[error] Undefined class 'C'. (package:test/src/frontend/expect_async.dart, line
33, col 26)
[error] Undefined class 'D'. (package:test/src/frontend/expect_async.dart, line
33, col 31)
[error] Undefined class 'E'. (package:test/src/frontend/expect_async.dart, line
33, col 36)
[error] Undefined class 'F'. (package:test/src/frontend/expect_async.dart, line
33, col 41)
[error] The argument type 'List' can't be assigned to the parameter type
'FutureOr<List<T>>'. (package:test/src/util/stream_queue.dart, line 514, col 25)
[error] The argument type 'List' can't be assigned to the parameter type
'FutureOr<List<T>>'. (package:test/src/util/stream_queue.dart, line 519, col 25)

 
 class DoubleTransformer<T> implements StreamTransformer<T, T> {
   Stream<T> bind(Stream<T> stream) {
     var transformer = new StreamTransformer<T, T>.fromHandlers(
         handleData: (T data, EventSink<T> sink) {
       sink.add(data);
       sink.add(data);
     });
     return transformer.bind(stream);
   }
 }
 
 main() {
   test("Double event before first", () {
     // This should not crash. Did crash by trying to complete future more
     // than once.
     new Stream.fromIterable([1, 2])
         .transform(new DoubleTransformer())
         .first
         .then(expectAsync((e) {}));
   });
 }