Check `await for` + stream works

readme.md

Check await for + stream works

Created with <3 with dartpad.dev.

• If we use _handle1, consume the message synchronous.
• If we use _handle2, consume the message parallel.

main.dart

import 'dart:async';

void main() {
  final controller = StreamController<String>();
  
  _handle1(controller.stream);
//   _handle2(controller.stream);

  controller.sink.add('message 1');
  controller.sink.add('message 2');
  controller.sink.add('message 3');
}

// output: "start:message 1" -> 2 seconds -> "end:message 1" -> "start:message 2" -> 2 seconds -> ...
Future<void> _handle1(Stream<String> stream) async {
  await for (var value in stream) {
    await _testLongProcess(value);
  }
}

// output: "start:message 1" -> "start:message 2" -> "start:message 3" -> 2 seconds -> "end:message 1" -> "end:message 2" -> ...
Future<void> _handle2(Stream<String> stream) async {
  stream.listen((data) async => await _testLongProcess(data));
}

Future<void> _testLongProcess(String message) async {
    print('_testLongProcess start：$message');
    await Future.delayed(const Duration(seconds: 2));
    print('_testLongProcess end  ：$message');
}