Add a FileStorage class

With a test!

lib/file_storage.dart

@@ -0,0 +1,51 @@
+import 'dart:async';
+import 'dart:io';
+import 'dart:convert';
+
+import 'package:path/path.dart' as p;
+
+import './note.dart';
+
+class FileStorage {
+  final Future<Directory> Function() getDirectory;
+
+  FileStorage(this.getDirectory);
+
+  Future<List<Note>> loadNotes() async {
+    final dir = await getDirectory();
+
+    var notes = new List<Note>();
+    var lister = dir.list(recursive: false);
+    await for (var fileEntity in lister) {
+      Note note = await _loadNote(fileEntity);
+      notes.add(note);
+    }
+
+    return notes;
+  }
+
+  Future<Note> _loadNote(FileSystemEntity entity) async {
+    if (entity is! File) {
+      return null;
+    }
+    var file = entity as File;
+    final string = await file.readAsString();
+    final json = JsonDecoder().convert(string);
+    return new Note.fromJson(json);
+  }
+
+  Future<Directory> saveNotes(List<Note> notes) async {
+    final dir = await getDirectory();
+    //await dir.delete(recursive: true);
+
+    for (var note in notes) {
+      var filePath = p.join(dir.path, note.id);
+
+      var file = new File(filePath);
+      var contents = JsonEncoder().convert(note.toJson());
+      await file.writeAsString(contents);
+    }
+
+    return dir;
+  }
+}

lib/note.dart

@@ -1,13 +1,43 @@
-class Note {
+class Note implements Comparable {
+  final String id;
   final DateTime createdAt;
   final String body;
 
-  const Note({this.createdAt, this.body});
+  const Note({this.createdAt, this.body, this.id});
 
   factory Note.fromJson(Map<String, dynamic> json) {
     return new Note(
+      id: json['id'],
       createdAt: DateTime.parse(json['createdAt']),
       body: json['body'],
     );
   }
+
+  Map<String, dynamic> toJson() {
+    return {
+      "createdAt": createdAt.toIso8601String(),
+      "body": body,
+      "id": id,
+    };
+  }
+
+  @override
+  int get hashCode => id.hashCode ^ createdAt.hashCode ^ body.hashCode;
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Note &&
+          runtimeType == other.runtimeType &&
+          id == other.id &&
+          body == other.body &&
+          createdAt == other.createdAt;
+
+  @override
+  String toString() {
+    return 'Note{id: $id, body: $body, createdAt: $createdAt}';
+  }
+
+  @override
+  int compareTo(other) => createdAt.compareTo(other.createdAt);
 }

pubspec.lock

@@ -222,7 +222,7 @@ packages:
     source: hosted
     version: "1.0.2"
   path:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: path
       url: "https://pub.dartlang.org"

pubspec.yaml

@@ -6,7 +6,7 @@ dependencies:
     sdk: flutter
   http: "^0.11.3+16"
   intl: "^0.15.6"
-
+  path: "^1.5.1"
 
 dev_dependencies:
   flutter_test:

test/file_storage_test.dart

@@ -0,0 +1,40 @@
+import 'dart:io';
+
+import 'package:test/test.dart';
+import 'package:path/path.dart' as p;
+
+import '../lib/note.dart';
+import '../lib/file_storage.dart';
+
+main() {
+  group('FileStorage', () {
+    var notes = [
+      Note(id: "1", body: "test", createdAt: new DateTime.now()),
+      Note(id: "2", body: "test2", createdAt: new DateTime.now()),
+    ];
+
+    final directory = Directory.systemTemp.createTemp('__storage_test__');
+    final storage = FileStorage(() => directory);
+
+    tearDownAll(() async {
+      final tempDirectory = await directory;
+      tempDirectory.deleteSync(recursive: true);
+    });
+
+    test('Should persist Notes to disk', () async {
+      var dir = await storage.saveNotes(notes);
+      expect(dir.listSync(recursive: true).length, 2);
+
+      expect(File(p.join(dir.path, "1")).existsSync(), isTrue);
+      expect(File(p.join(dir.path, "2")).existsSync(), isTrue);
+    });
+
+    test('Should load Notes from disk', () async {
+      var loadedNotes = await storage.loadNotes();
+      loadedNotes.sort();
+      notes.sort();
+
+      expect(loadedNotes, notes);
+    });
+  });
+}

test/widget_test.dart

@@ -1,29 +0,0 @@
-// This is a basic Flutter widget test.
-// To perform an interaction with a widget in your test, use the WidgetTester utility that Flutter
-// provides. For example, you can send tap and scroll gestures. You can also use WidgetTester to
-// find child widgets in the widget tree, read text, and verify that the values of widget properties
-// are correct.
-
-import 'package:flutter/material.dart';
-import 'package:flutter_test/flutter_test.dart';
-
-import 'package:journal/main.dart';
-
-void main() {
-  testWidgets('Counter increments smoke test', (WidgetTester tester) async {
-    // Build our app and trigger a frame.
-    await tester.pumpWidget(new MyApp());
-
-    // Verify that our counter starts at 0.
-    expect(find.text('0'), findsOneWidget);
-    expect(find.text('1'), findsNothing);
-
-    // Tap the '+' icon and trigger a frame.
-    await tester.tap(find.byIcon(Icons.add));
-    await tester.pump();
-
-    // Verify that our counter has incremented.
-    expect(find.text('0'), findsNothing);
-    expect(find.text('1'), findsOneWidget);
-  });
-}