packages/camera/camera_android/test/method_channel_mock.dart

// Copyright 2013 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 'package:flutter/services.dart';
import 'package:flutter_test/flutter_test.dart';

class MethodChannelMock {
  MethodChannelMock({
    required String channelName,
    this.delay,
    required this.methods,
  }) : methodChannel = MethodChannel(channelName) {
    _ambiguate(TestDefaultBinaryMessengerBinding.instance)!
        .defaultBinaryMessenger
        .setMockMethodCallHandler(methodChannel, _handler);
  }

  final Duration? delay;
  final MethodChannel methodChannel;
  final Map<String, dynamic> methods;
  final List<MethodCall> log = <MethodCall>[];

  Future<dynamic> _handler(MethodCall methodCall) async {
    log.add(methodCall);

    if (!methods.containsKey(methodCall.method)) {
      throw MissingPluginException('No implementation found for method '
          '${methodCall.method} on channel ${methodChannel.name}');
    }

    return Future<dynamic>.delayed(delay ?? Duration.zero, () {
      final dynamic result = methods[methodCall.method];
      if (result is Exception) {
        throw result;
      }

      return Future<dynamic>.value(result);
    });
  }
}

/// This allows a value of type T or T? to be treated as a value of type T?.
///
/// We use this so that APIs that have become non-nullable can still be used
/// with `!` and `?` on the stable branch.
T? _ambiguate<T>(T? value) => value;