Dart 小部件测试失败，未找到MediaQuery小部件

我的问题是关于颤振小部件测试，测试现有小部件的正确方法是什么？我找到了

MediaQuery.of

，但它接受

BuildContext

而不是

Widget

详细信息：我已经编写了简单的登录表单小部件，并尝试为其实现小部件测试。执行测试后，我得到异常：

Expected: 'Sorry, only customer can login from mobile device. [Mock]'
  Actual: FlutterError:<No MediaQuery widget found.
          Scaffold widgets require a MediaQuery widget ancestor.
          The specific widget that could not find a MediaQuery ancestor was:
            Scaffold-[LabeledGlobalKey<ScaffoldState>#8ffee]
          The ownership chain for the affected widget is:
            Scaffold-[LabeledGlobalKey<ScaffoldState>#8ffee] ← LoginForm ← [root]
          Typically, the MediaQuery widget is introduced by the MaterialApp or WidgetsApp widget at
          the top of your application widget tree.>
   Which: FlutterError:<No MediaQuery widget found.
          Scaffold widgets require a MediaQuery widget ancestor.
          The specific widget that could not find a MediaQuery ancestor was:
            Scaffold-[LabeledGlobalKey<ScaffoldState>#8ffee]
          The ownership chain for the affected widget is:
            Scaffold-[LabeledGlobalKey<ScaffoldState>#8ffee] ← LoginForm ← [root]
          Typically, the MediaQuery widget is introduced by the MaterialApp or WidgetsApp widget at
          the top of your application widget tree.>is not a string

When the exception was thrown, this was the stack:
#4      main.<anonymous closure> (C:\Work\app_mobile\test\login_widget_test.dart:21:5)
<asynchronous suspension>
#5      testWidgets.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:flutter_test\src\widget_tester.dart:61:25)
#6      TestWidgetsFlutterBinding._runTestBody (package:flutter_test\src\binding.dart:471:19)
<asynchronous suspension>
#9      TestWidgetsFlutterBinding._runTest (package:flutter_test\src\binding.dart:458:14)
#10     AutomatedTestWidgetsFlutterBinding.runTest.<anonymous closure> (package:flutter_test\src\binding.dart:640:24)
#11     _FakeAsync.run.<anonymous closure> (package:quiver\testing\src\async\fake_async.dart:186:24)
#15     _FakeAsync.run (package:quiver\testing\src\async\fake_async.dart:185:11)
#16     AutomatedTestWidgetsFlutterBinding.runTest (package:flutter_test\src\binding.dart:638:16)
#17     testWidgets.<anonymous closure>.<anonymous closure> (package:flutter_test\src\widget_tester.dart:60:24)
#18     Declarer.test.<anonymous closure>.<anonymous closure> (package:test\src\backend\declarer.dart:160:19)
<asynchronous suspension>
#19     Invoker.waitForOutstandingCallbacks.<anonymous closure> (package:test\src\backend\invoker.dart:206:15)
<asynchronous suspension>
#23     Invoker.waitForOutstandingCallbacks (package:test\src\backend\invoker.dart:203:5)
#24     Declarer.test.<anonymous closure> (package:test\src\backend\declarer.dart:158:29)
<asynchronous suspension>
#25     Invoker._onRun.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:test\src\backend\invoker.dart:351:23)
<asynchronous suspension>
#27     StackZoneSpecification._run (package:stack_trace\src\stack_zone_specification.dart:209:15)
#28     StackZoneSpecification._registerCallback.<anonymous closure> (package:stack_trace\src\stack_zone_specification.dart:119:48)
#33     StackZoneSpecification._run (package:stack_trace\src\stack_zone_specification.dart:209:15)
#34     StackZoneSpecification._registerCallback.<anonymous closure> (package:stack_trace\src\stack_zone_specification.dart:119:48)
#39     _Timer._runTimers (dart:isolate-patch/dart:isolate/timer_impl.dart:367)
#40     _Timer._handleMessage (dart:isolate-patch/dart:isolate/timer_impl.dart:401)
#41     _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:163)
(elided 17 frames from package dart:async and package dart:async-patch)

---

我找到了的

MediaQuery.of，但不明白如何将它与现有的小部件一起使用？它接受
BuildContext
作为参数。
您需要使用
MediaQuery（…）
实例包装您的小部件，因为您使用的是
Scaffold（…）
您必须将其包装在
MaterialApp（…）


示例：

Widget testWidget = new MediaQuery(
      data: new MediaQueryData(),
      child: new MaterialApp(home: new LoginForm())
)

我也有同样的问题，我还必须用MaterialApp包装它，但我用了另一种方式，没有使用MediaQuery。就我而言，它是有效的

void main() {

Widget createWidgetForTesting({Widget child}){
return MaterialApp(
  home: child,
);
}

testWidgets('Login Page smoke test', (WidgetTester tester) async {

await tester.pumpWidget(createWidgetForTesting(child: new LoginPage()));

await tester.pumpAndSettle();

});
}

**scaffold（）小部件如何成为MaterialApp（）的子部件的完美示例
**

导入“包装：颤振/材料.省道”；
类MyApp扩展了无状态小部件{
@凌驾
小部件构建（构建上下文）{
返回材料PP(
debugShowCheckedModeBanner:false，
主题：主题数据(
主样本：颜色。蓝色，
),
主页：我的主页（标题：“标题”），
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage（{Key，this.title}）：超级（Key:Key）；
@凌驾
_MyHomePageState createState（）=>\u MyHomePageState（）；
}
类_MyHomePageState扩展状态{
小部件构建（构建上下文）{
归还新脚手架(
appBar:appBar(
背景颜色：颜色。透明，
标题：widget.title
)
}
与下面@nknezevic提出的解决方案相比，您的解决方案有什么优势吗？MediaQuery的文档声明MaterialApp和WidgetsApp引入了MediaQuery。我是一个noob，所以我很想理解。否则，下面的答案似乎更可取，因为它是一个更干净、更简单的解决方案，或者只是简单地用一个MaterialApp。它应该像testWidget=MaterialApp（home:LoginForm（））；@David Shuma谢谢你的工作
Widget testWidget = new MediaQuery(
      data: new MediaQueryData(),
      child: new MaterialApp(home: new LoginForm())
)

void main() {

Widget createWidgetForTesting({Widget child}){
return MaterialApp(
  home: child,
);
}

testWidgets('Login Page smoke test', (WidgetTester tester) async {

await tester.pumpWidget(createWidgetForTesting(child: new LoginPage()));

await tester.pumpAndSettle();

});
}

          import 'package:flutter/material.dart';
   
         class MyApp extends StatelessWidget {

             @override
          Widget build(BuildContext context) {
        return MaterialApp(
         debugShowCheckedModeBanner: false,
           theme: ThemeData(
      primarySwatch: Colors.blue,
      ),
     home: MyHomePage(title: 'title'),
    );
  }
}

        class MyHomePage extends StatefulWidget {
        MyHomePage({Key Key, this.title}) : super(key: Key);

       @override
        _MyHomePageState createState() => _MyHomePageState();

    }

        class _MyHomePageState extends State<MyHomePage> {
    Widget build(BuildContext context) {
      return new Scaffold(
     appBar: AppBar(
    backgroundColor: Colors.transparent,
    title: widget.title
 )

}