Question

我在Flutter网站上阅读了introduction to platform-specific plugins/channels，我浏览了一些简单的插件示例，例如url_launcher：

// Copyright 2017 The Chromium 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/services.dart';

const _channel = const MethodChannel('plugins.flutter.io/url_launcher');

/// Parses the specified URL string and delegates handling of it to the
/// underlying platform.
///
/// The returned future completes with a [PlatformException] on invalid URLs and
/// schemes which cannot be handled, that is when [canLaunch] would complete
/// with false.
Future<Null> launch(String urlString) {
  return _channel.invokeMethod(
    'launch',
    urlString,
  );
}

在小部件测试或集成测试中，我如何模拟或存根通道，以便我不必依赖真实设备（运行Android或iOS）说，实际上是启动URL？

Answer 1

您可以使用setMockMethodCallHandler为基础方法通道注册模拟处理程序：

https://docs.flutter.io/flutter/services/MethodChannel/setMockMethodCallHandler.html

final List<MethodCall> log = <MethodCall>[];

MethodChannel channel = const MethodChannel('plugins.flutter.io/url_launcher');

// Register the mock handler.
channel.setMockMethodCallHandler((MethodCall methodCall) async {
  log.add(methodCall);
});

await launch("http://example.com/");

expect(log, equals(<MethodCall>[new MethodCall('launch', "http://example.com/")]));

// Unregister the mock handler.
channel.setMockMethodCallHandler(null);

Answer 2

创建插件时，系统会自动为您提供默认测试：

function ToCamelCase(data) {
    data['string'] = data['string'].replace(/(?:\s|^)(\w+)(?=\s|$)/g, function(word, index) {
        var lowerWord = word.toLowerCase().trim();
        return lowerWord.substring(0, 1).toUpperCase() + lowerWord.substring(1, word.length) + " "
    });
    if (data['remSpace']) {
        data['string'] = data['string'].replace(/\s/g, '');
    }
    return data['string'];
}

让我为此添加一些注释：

调用void main() { const MethodChannel channel = MethodChannel('my_plugin'); setUp(() { channel.setMockMethodCallHandler((MethodCall methodCall) async { return '42'; }); }); tearDown(() { channel.setMockMethodCallHandler(null); }); test('getPlatformVersion', () async { expect(await MyPlugin.platformVersion, '42'); }); }可使您绕过实际插件的工作，并返回自己的值。
您可以使用setMockMethodCallHandler区分方法，methodCall.method是被调用方法名称的字符串。
对于插件创建者来说，这是一种验证公共API名称的方法，但它不会测试API的功能。您需要为此使用集成测试。

Answer 3

MethodChannel#setMockMethodCallHandler 现已弃用并删除。

看起来这是现在要走的路：

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

void mockUrlLauncher() {
  const channel = MethodChannel('plugins.flutter.io/url_launcher');

  handler(MethodCall methodCall) async {
    if (methodCall.method == 'yourMethod') {
      return 42;
    }
    return null;
  }

  TestWidgetsFlutterBinding.ensureInitialized();

  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
      .setMockMethodCallHandler(channel, handler);
}

详情见GitHub。

这里是一个经过测试的 package_info 插件示例，以供将来参考：

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

void mockPackageInfo() {
  const channel = MethodChannel('plugins.flutter.io/package_info');

  handler(MethodCall methodCall) async {
    if (methodCall.method == 'getAll') {
      return <String, dynamic>{
        'appName': 'myapp',
        'packageName': 'com.mycompany.myapp',
        'version': '0.0.1',
        'buildNumber': '1'
      };
    }
    return null;
  }

  TestWidgetsFlutterBinding.ensureInitialized();

  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
      .setMockMethodCallHandler(channel, handler);
}

我如何模拟/存根Flutter平台频道/插件？

3 个答案: