blob: cde1928f962aecf54974f1bb69b2c9856d602115 [file] [log] [blame]
// Copyright (c) 2015, 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:async/async.dart';
import 'package:test/test.dart';
import 'utils.dart';
void main() {
test('calls the callback when the stream is listened', () async {
var callbackCalled = false;
var stream = LazyStream(expectAsync0(() {
callbackCalled = true;
return Stream.empty();
}));
await flushMicrotasks();
expect(callbackCalled, isFalse);
stream.listen(null);
expect(callbackCalled, isTrue);
});
test('calls the callback when the stream is listened', () async {
var callbackCalled = false;
var stream = LazyStream(expectAsync0(() {
callbackCalled = true;
return Stream.empty();
}));
await flushMicrotasks();
expect(callbackCalled, isFalse);
stream.listen(null);
expect(callbackCalled, isTrue);
});
test('forwards to a synchronously-provided stream', () async {
var controller = StreamController<int>();
var stream = LazyStream(expectAsync0(() => controller.stream));
var events = [];
stream.listen(events.add);
controller.add(1);
await flushMicrotasks();
expect(events, equals([1]));
controller.add(2);
await flushMicrotasks();
expect(events, equals([1, 2]));
controller.add(3);
await flushMicrotasks();
expect(events, equals([1, 2, 3]));
controller.close();
});
test('forwards to an asynchronously-provided stream', () async {
var controller = StreamController<int>();
var stream = LazyStream(expectAsync0(() async => controller.stream));
var events = [];
stream.listen(events.add);
controller.add(1);
await flushMicrotasks();
expect(events, equals([1]));
controller.add(2);
await flushMicrotasks();
expect(events, equals([1, 2]));
controller.add(3);
await flushMicrotasks();
expect(events, equals([1, 2, 3]));
controller.close();
});
test("a lazy stream can't be listened to multiple times", () {
var stream = LazyStream(expectAsync0(Stream.empty));
expect(stream.isBroadcast, isFalse);
stream.listen(null);
expect(() => stream.listen(null), throwsStateError);
expect(() => stream.listen(null), throwsStateError);
});
test("a lazy stream can't be listened to from within its callback", () {
late LazyStream stream;
stream = LazyStream(expectAsync0(() {
expect(() => stream.listen(null), throwsStateError);
return Stream.empty();
}));
stream.listen(null);
});
}