Migrate async tests to strong

tests/lib_strong/async/stream_iterator_test.dart

+// 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.
+
+import "dart:async";
+import "package:unittest/unittest.dart";
+
+main() {
+  test("stream iterator basic", () async {
+    var stream = createStream();
+    StreamIterator iterator = new StreamIterator(stream);
+    expect(iterator.current, isNull);
+    expect(await iterator.moveNext(), isTrue);
+    expect(iterator.current, 42);
+    expect(await iterator.moveNext(), isTrue);
+    expect(iterator.current, 37);
+    expect(await iterator.moveNext(), isFalse);
+    expect(iterator.current, isNull);
+    expect(await iterator.moveNext(), isFalse);
+  });
+
+  test("stream iterator prefilled", () async {
+    Stream stream = createStream();
+    StreamIterator iterator = new StreamIterator(stream);
+    await new Future.delayed(Duration.ZERO);
+    expect(iterator.current, isNull);
+    expect(await iterator.moveNext(), isTrue);
+    expect(iterator.current, 42);
+    expect(await iterator.moveNext(), isTrue);
+    expect(iterator.current, 37);
+    expect(await iterator.moveNext(), isFalse);
+    expect(iterator.current, isNull);
+    expect(await iterator.moveNext(), isFalse);
+  });
+
+  test("stream iterator error", () async {
+    Stream stream = createErrorStream();
+    StreamIterator iterator = new StreamIterator(stream);
+    expect(await iterator.moveNext(), isTrue);
+    expect(iterator.current, 42);
+    var hasNext = iterator.moveNext();
+    expect(hasNext, throwsA("BAD"));  // This is an async expectation,
+    await hasNext.catchError((_){});  // so we have to wait for the future too.
+    expect(iterator.current, isNull);
+    expect(await iterator.moveNext(), isFalse);
+    expect(iterator.current, isNull);
+  });
+
+  test("stream iterator current/moveNext during move", () async {
+    Stream stream = createStream();
+    StreamIterator iterator = new StreamIterator(stream);
+    var hasNext = iterator.moveNext();
+    expect(iterator.moveNext, throwsA(isStateError));
+    expect(await hasNext, isTrue);
+    expect(iterator.current, 42);
+    iterator.cancel();
+  });
+
+  test("stream iterator error during cancel", () async {
+    Stream stream = createCancelErrorStream();
+    StreamIterator iterator = new StreamIterator(stream);
+    for (int i = 0; i < 10; i++) {
+      expect(await iterator.moveNext(), isTrue);
+      expect(iterator.current, i);
+    }
+    var hasNext = iterator.moveNext();  // active moveNext will be completed.
+    var cancel = iterator.cancel();
+    expect(cancel, throwsA("BAD"));
+    expect(await hasNext, isFalse);
+      expect(await iterator.moveNext(), isFalse);
+  });
+
+}
+
+Stream createStream() async* {
+  yield 42;
+  yield 37;
+}
+
+Stream createErrorStream() async* {
+  yield 42;
+  // Emit an error without stopping the generator.
+  yield* (new Future.error("BAD").asStream());
+  yield 37;
+}
+
+/// Create a stream that throws when cancelled.
+Stream createCancelErrorStream() async* {
+  int i = 0;
+  try {
+    while (true) yield i++;
+  } finally {
+    throw "BAD";
+  }
+}