flutter_cache_store test boilerplate

echo_http_server.dart

import 'dart:convert';
import 'dart:io';
import 'dart:developer';

const HEADERS = {
  'Content-Type': 'application/json',
  'Cache-Control': 'max-age=120',
};

const PORT = 2020;

class EchoHttpServer {
  static HttpServer _server;
  HttpServer get server => _server;

  Future<void> echo(HttpRequest req) async {
    final res = req.response;
    HEADERS.forEach((name, value) {
      res.headers.add(name, value);
    });

    final uri = req.requestedUri;
    final ts = DateTime.now().toIso8601String();
    final params = uri.queryParameters;
    log('[ECHO $ts] $uri');
    final data = {
      'path': uri.path,
      'query': params,
      'ts': ts,
    };
    final size = int.tryParse(params['size'] ?? '0');
    if (size != null && size > 0) {
      data['payload'] = 'x' * (size * 1000);
    }

    res.write(json.encode(data));
    res.close();
  }

  Future<void> initialize() async {
    _server = await HttpServer.bind(InternetAddress.anyIPv4, PORT);
    _server.listen(echo);
  }
}

main.dart

import 'dart:convert';
import 'dart:developer';

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

import 'echo_http_server.dart';

CacheStore store;

void main() async {
  final server = EchoHttpServer();
  server.initialize();
  runApp(MyApp());
}

const REQUESTS = [
  'http://localhost:$PORT/foo?foo=foo&size=3',
  'http://localhost:$PORT/bar?bar=bar',
  'http://localhost:$PORT/baz?baz=baz&size=20',
  'http://localhost:$PORT/foo_bar?foo_bar=foo_bar',
  'http://localhost:$PORT/foo_baz?foo_baz=foo_baz&size=100',
  'http://localhost:$PORT/bar_baz?bar_baz=bar_baz',
];

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  String _json = '';

  _MyHomePageState() {
    initStore();
  }

  Future<void> initStore() async {
    if (store != null) return;

    store = await CacheStore.getInstance(
      policy: CacheControlPolicy(
        maxCount: 3,
        maxAge: const Duration(seconds: 100),
      ),
    );
    print('path ${store.path}');
  }

  void _incrementCounter() async {
    final url = REQUESTS[_counter % REQUESTS.length];
    final ts = DateTime.now().toIso8601String();

    log('[FETCH $ts] $url');
    final file = await store.getFile(url);
    final data = file.readAsStringSync();
    final timestamp = json.decode(data)['ts'];
    log('[RESPONSE] size=${data.length} timestamp=$timestamp');

    setState(() {
      _counter++;
      _json = data.length > 1000
          ? '(size=${data.length} timestamp=$timestamp)'
          : data;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times: $_counter',
            ),
            Text('JSON: $_json'),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}