使用Future.delayed时测试中断

Question

我使用了Future.delayed以下代码，在1秒内显示了FAB：

Future.delayed(const Duration(seconds: 1), () {
  setState(() {
    _showFab = true;
  });
});

现在，最基本的烟雾测试已停止工作：

void main() {
  testWidgets('smoke test', (WidgetTester tester) async {
    await tester.pumpWidget(MyApp());

    expect(find.byType(MyHomePage), findsOneWidget);
  });
}

这是错误消息：

??? EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ?????????????????????????????????????????????????????
The following assertion was thrown running a test:
A Timer is still pending even after the widget tree was disposed.
'package:flutter_test/src/binding.dart': Failed assertion: line 933 pos 7:
'_currentFakeAsync.nonPeriodicTimerCount == 0'    import 'dart:async';

这是所有使用的代码：

import 'package:flutter/material.dart';
import 'dart:async';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {
  bool _showFab = false;

  @override
  Widget build(BuildContext context) {
    Future.delayed(const Duration(seconds: 1), () {
      setState(() {
        _showFab = true;
      });
    });

    return Scaffold(
      floatingActionButton: AnimatedOpacity(
        opacity: _showFab ? 1.0 : 0.0,
        duration: Duration(milliseconds: 1400),
        child: FloatingActionButton(
          onPressed: null,
          child: Icon(Icons.add),
        ),
      ),
    );
  }
}

如何更改单元测试以使测试通过？

Answer 1

测试框架FakeAsync默认运行，它有一些限制，可能会导致你得到的错误。

您可以显式地使用异步正确运行，例如：

void main() {
  testWidgets('smoke test', (WidgetTester tester) async {
    await tester.runAsync(() async {
      await tester.pumpWidget(MyApp());

      expect(find.byType(MyHomePage), findsOneWidget);
    });
  });
}

您可能仍需要其他答案中提出的建议。

Answer 2

您可以使用TickerMode包装您的 Widget 。

如下所示：

void main() {
    testWidgets('smoke test', (WidgetTester tester) async {
    await tester.pumpWidget(TickerMode(child: MyApp(), enabled: false));
    await tester.pumpAndSettle();
    expect(find.byType(MyHomePage), findsOneWidget);
  });
}

Answer 3

尝试在泵送小部件后调用PumpAndSettle 。像这样：

void main() {
  testWidgets('smoke test', (WidgetTester tester) async {
    await tester.pumpWidget(MyApp());
    await tester.pumpAndSettle();

    expect(find.byType(MyHomePage), findsOneWidget);
  });
}

来自文档

这本质上是等待所有动画完成。

Answer 4

您需要给测试人员足够的时间来处理您计划的所有异步调用，尝试将冒烟测试更改为以下内容：

void main() {
    testWidgets('smoke test', (WidgetTester tester) async {
    await tester.pumpWidget(MyApp());
    // Since you wait 1 second to start the animation and another 1.4 to complete it
    await tester.pump(Duration(seconds: 3));

    expect(find.byType(MyHomePage), findsOneWidget);
  });
}

您还需要移动Future.delayed出的build()方法，因为这是造成循环的行为，您拨打每次setState()将build()被再次调用，改变一样，您的状态：

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {
  bool _showFab = false;

  @override
  void initState() {
    Future.delayed(const Duration(seconds: 1), () {
      setState(() {
        _showFab = true;
      });
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: AnimatedOpacity(
        opacity: _showFab ? 1.0 : 0.0,
        duration: Duration(milliseconds: 1400),
        child: FloatingActionButton(
          onPressed: null,
          child: Icon(Icons.add),
        ),
      ),
    );
  }
}