颤振测试shared_preferences

Question

我正在编写一个颤振应用程序，在编写测试时遇到了这个问题。该方法应该将数据写入TextFields并点击一个按钮将数据保存在SharedPrefs中：

testWidgets('Click on login saves the credentials',
      (WidgetTester tester) async {

    await tester.pumpWidget(MyApp());

    await tester.enterText(find.byKey(Key('phoneInput')), 'test');
    await tester.enterText(find.byKey(Key('passwordInput')), 'test');
    await tester.tap(find.byIcon(Icons.lock));

    SharedPreferences prefs = await SharedPreferences.getInstance();
    expect(prefs.getString('phone'), 'test');
    expect(prefs.getString('password'), 'test');
  });

此测试将无法获得包含此错误的SharedPreferences实例：

The following TimeoutException was thrown running a test:
TimeoutException after 0:00:03.500000: The test exceeded the timeout. It may have hung.
Consider using "addTime" to increase the timeout before expensive operations.

Update:似乎问题不在于超时，因为即使有60秒的时间，测试也无法解决SharedPreferences实例。

Answer 1

您可以使用提供的模拟setMockInitialValues。

testWidgets('Click on login saves the credentials',
      (WidgetTester tester) async {

    await tester.pumpWidget(MyApp());

    SharedPreferences.setMockInitialValues(<String, dynamic>{
      'flutter.phone': '',
      'flutter.password': '',
    });

    await tester.enterText(find.byKey(Key('phoneInput')), 'test');
    await tester.enterText(find.byKey(Key('passwordInput')), 'test');
    await tester.tap(find.byIcon(Icons.lock));

    SharedPreferences prefs = await SharedPreferences.getInstance();
    expect(prefs.getString('phone'), 'test');
    expect(prefs.getString('password'), 'test');
  });

Answer 2

正如在github中提到的，您可以在测试开始时这样做：

tester.addTime(const Duration(seconds: 10));

下面是链接和完整的示例：https://github.com/flutter/flutter/issues/19175

testWidgets('MyWidget', (WidgetTester tester) async {
  final AutomatedTestWidgetsFlutterBinding binding = tester.binding;
  binding.addTime(const Duration(seconds: 10)); // or longer if needed
  await tester.pumpWidget(new MyWidget());
  await tester.tap(find.text('Save'));
  expect(find.text('Success'), findsOneWidget);
});

Answer 3

TruongSinh提供的解决方案不适合我。当我试图从代码(而不是测试)中将值设置为SharedPreferences时，我得到了错误。

这是对这个答案的补充。您需要自己重新实现setter：

import 'package:flutter/services.dart';

void main() {

  setUpAll(() {
    final values = <String, dynamic>{};  // set initial values here if desired
    const MethodChannel('plugins.flutter.io/shared_preferences')
        .setMockMethodCallHandler((MethodCall methodCall) async {
      if (methodCall.method == 'getAll') {
        return values;
      } else if (methodCall.method.startsWith("set")) {
        values[methodCall.arguments["key"]] = methodCall.arguments["value"];
        return true;
      }
      return null;
    });
  });

  testWidgets('Test if your code works as designed', (WidgetTester tester) async {
    ...
  });

}