Liam Appelbe
70f6e6553c
It seems that there's some fiddliness when writing error handling lambdas in strong mode. async_await_sync_completer_test: The lambda was implicitly trying to return the result of a throw, which was Never. I've switched it to this syntax, which implicitly returns Null instead. stream_iterator_test: The error handler needs to return a Bool, for compatibility with the Future. I'm open to suggestions for cleaner fixes to these bugs. Change-Id: Ifc646a965d4b435512277da96ffb5e0b429114cb Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/141164 Commit-Queue: Liam Appelbe <liama@google.com> Reviewed-by: Régis Crelier <regis@google.com> Reviewed-by: Alexander Markov <alexmarkov@google.com>
99 lines
3.1 KiB
Dart
99 lines
3.1 KiB
Dart
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import 'dart:async';
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import 'package:async_helper/async_minitest.dart';
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main() {
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test("stream iterator basic", () async {
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var stream = createStream();
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StreamIterator iterator = new StreamIterator(stream);
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expect(iterator.current, isNull);
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expect(await iterator.moveNext(), isTrue);
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expect(iterator.current, 42);
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expect(await iterator.moveNext(), isTrue);
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expect(iterator.current, 37);
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expect(await iterator.moveNext(), isFalse);
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expect(iterator.current, isNull);
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expect(await iterator.moveNext(), isFalse);
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});
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test("stream iterator prefilled", () async {
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Stream stream = createStream();
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StreamIterator iterator = new StreamIterator(stream);
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await new Future.delayed(Duration.zero);
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expect(iterator.current, isNull);
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expect(await iterator.moveNext(), isTrue);
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expect(iterator.current, 42);
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expect(await iterator.moveNext(), isTrue);
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expect(iterator.current, 37);
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expect(await iterator.moveNext(), isFalse);
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expect(iterator.current, isNull);
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expect(await iterator.moveNext(), isFalse);
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});
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test("stream iterator error", () async {
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Stream stream = createErrorStream();
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StreamIterator iterator = new StreamIterator(stream);
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expect(await iterator.moveNext(), isTrue);
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expect(iterator.current, 42);
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var hasNext = iterator.moveNext();
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expect(hasNext, throwsA("BAD")); // This is an async expectation,
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await hasNext.catchError((_) {
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// so we have to wait for the future too.
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return false;
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});
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expect(iterator.current, isNull);
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expect(await iterator.moveNext(), isFalse);
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expect(iterator.current, isNull);
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});
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test("stream iterator current/moveNext during move", () async {
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Stream stream = createStream();
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StreamIterator iterator = new StreamIterator(stream);
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var hasNext = iterator.moveNext();
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expect(iterator.moveNext, throwsStateError);
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expect(await hasNext, isTrue);
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expect(iterator.current, 42);
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iterator.cancel();
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});
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test("stream iterator error during cancel", () async {
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Stream stream = createCancelErrorStream();
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StreamIterator iterator = new StreamIterator(stream);
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for (int i = 0; i < 10; i++) {
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expect(await iterator.moveNext(), isTrue);
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expect(iterator.current, i);
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}
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var hasNext = iterator.moveNext(); // active moveNext will be completed.
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var cancel = iterator.cancel();
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expect(cancel, throwsA("BAD"));
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expect(await hasNext, isFalse);
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expect(await iterator.moveNext(), isFalse);
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});
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}
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Stream createStream() async* {
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yield 42;
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yield 37;
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}
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Stream createErrorStream() async* {
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yield 42;
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// Emit an error without stopping the generator.
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yield* (new Future.error("BAD").asStream());
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yield 37;
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}
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/// Create a stream that throws when cancelled.
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Stream createCancelErrorStream() async* {
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int i = 0;
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try {
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while (true) yield i++;
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} finally {
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throw "BAD";
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}
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}
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