flutter - 如何在颤振中测试保存的文件

Question

这个flutter网页读写文件

提供了保存文件的示例，在本例中包含一个计数器。我已将其粘贴到示例应用程序中。如何对文件保存部分进行单元测试？我失败的测试尝试低于应用程序代码。有2个问题：

1. 如何编写测试本身 - t = storage.writeCounter(counter); 的可测试返回是什么？

2. 如何关闭应用程序并证明文件存在并且以后可以读取

main.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';

void main() {
  runApp(
    MaterialApp(
      title: 'Reading and Writing Files',
      home: FlutterDemo(storage: CounterStorage()),
    ),
  );
}

class CounterStorage {
  Future<String> get _localPath async {
    final directory = await getApplicationDocumentsDirectory();

    return directory.path;
  }

  Future<File> get _localFile async {
    final path = await _localPath;
    return File('$path/counter.txt');
  }

  Future<int> readCounter() async {
    try {
      final file = await _localFile;

      // Read the file
      final contents = await file.readAsString();

      return int.parse(contents);
    } catch (e) {
      // If encountering an error, return 0
      return 0;
    }
  }

  Future<File> writeCounter(int counter) async {
    final file = await _localFile;

    // Write the file
    return file.writeAsString('$counter');
  }
}

class FlutterDemo extends StatefulWidget {
  const FlutterDemo({Key? key, required this.storage}) : super(key: key);

  final CounterStorage storage;

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

class _FlutterDemoState extends State<FlutterDemo> {
  int _counter = 0;

  @override
  void initState() {
    super.initState();
    widget.storage.readCounter().then((int value) {
      setState(() {
        _counter = value;
      });
    });
  }

  Future<File> _incrementCounter() {
    setState(() {
      _counter++;
    });

    // Write the variable as a string to the file.
    return widget.storage.writeCounter(_counter);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Reading and Writing Files'),
      ),
      body: Center(
        child: Text(
          'Button tapped $_counter time${_counter == 1 ? '' : 's'}.',
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

counter_test.dart

import 'package:write_file_test/main.dart';

void main() {
  test('Check file save works', () async {
    final CounterStorage storage;

    var counter = 6;
    var t = storage.writeCounter(counter);
    expect(find.text('1'), findsOneWidget);
  });
}

发布规范.yaml

name: write_file_test
description: Flutter test file saving

publish_to: 'none' # Remove this line if you wish to publish to pub.dev

version: 1.0.0+1

environment:
  sdk: ">=2.12.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

  path_provider: ^2.0.5
  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter

  flutter_lints: ^1.0.0

flutter:

  uses-material-design: true

标签： flutterunit-testingfile-io