packages/flutter/test/foundation/capture_output.dart

// Copyright 2014 The Flutter Authors. 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:flutter/foundation.dart';

List<String> captureOutput(VoidCallback fn) {
  final List<String> log = <String>[];

  runZoned<void>(fn, zoneSpecification: ZoneSpecification(
    print: (
      Zone self,
      ZoneDelegate parent,
      Zone zone,
      String line,
    ) {
      log.add(line);
    },
  ));

  return log;
}