💚 Conform Dart team's pedantic linting rule and then some

.travis.yml

@@ -14,6 +14,7 @@ install:
   - flutter doctor -v
   - flutter packages get
 script:
+  - flutter analyze --no-pub --no-current-package lib/ test/
   - flutter test --coverage --coverage-path=lcov.info
 after_success:
   - bash <(curl -s https://codecov.io/bash)

README.md

@@ -2,14 +2,14 @@
 
 [![Build Status](https://travis-ci.com/toureh/flutter_workshop.svg?branch=master)](https://travis-ci.com/toureh/flutter_workshop)
 [![codecov](https://codecov.io/gh/toureh/flutter_workshop/branch/master/graph/badge.svg)](https://codecov.io/gh/toureh/flutter_workshop)
+[![Lint](https://img.shields.io/badge/style-pedantic-blue.svg)](https://github.com/dart-lang/pedantic)
 
-This repository contains a sample app the I use to give workshops geared towards beginners to Flutter. I've made an effort to keep the git history clean so that each commit represents a significant building block in the app.
+This repository contains a sample app that I use to give workshops geared towards beginners to Flutter. I've made an effort to keep the git history clean by doing cohesive commits that each represent a teachable building block in the app.
 
 
 ## Contains examples of:
 
-* Basic widgets
-* Building layouts
+* Basic widgets and building layouts
 * Internationalization
 * Navigation & routing
 * Networking
@@ -18,6 +18,7 @@ This repository contains a sample app the I use to give workshops geared towards
 * Storing key-value data on disk
 * Dependency injection with InheritedWidget
 * Unit and widget tests
+* Configuring linting rules to implement the Effective Dart guidelines
 * Continuous integration pipelines with Travis CI
 * Uploading code coverage to Codecov
 

analysis_options.yaml

@@ -0,0 +1,49 @@
+# All Google internally enforced app development rules and some Flutter SDK development rules
+
+# https://raw.githubusercontent.com/dart-lang/pedantic/master/lib/analysis_options.1.7.0.yaml
+# https://github.com/flutter/flutter/blob/master/analysis_options.yaml
+
+linter:
+  rules:
+    - always_declare_return_types # Flutter SDK style
+    - avoid_empty_else
+    - avoid_init_to_null
+    - avoid_relative_lib_imports
+    - avoid_return_types_on_setters
+    - avoid_shadowing_type_parameters
+    - avoid_types_as_parameter_names
+    - await_only_futures # Flutter SDK style
+    - camel_case_types # Flutter SDK style
+    - cancel_subscriptions # Flutter SDK style
+    - curly_braces_in_flow_control_structures
+    - empty_catches
+    - empty_constructor_bodies
+    - library_names
+    - library_prefixes
+    - no_duplicate_case_values
+    - null_closures
+    - prefer_const_constructors # Flutter SDK style
+    - prefer_const_constructors_in_immutables # Flutter SDK style
+    - prefer_const_declarations # Flutter SDK style
+    - prefer_const_literals_to_create_immutables # Flutter SDK style
+    - prefer_contains
+    - prefer_equal_for_default_values
+    - prefer_is_empty
+    - prefer_is_not_empty
+    - recursive_getters
+    - slash_for_doc_comments
+    - type_init_formals
+    - unawaited_futures
+    - unnecessary_brace_in_string_interps # Flutter SDK style
+    - unnecessary_const # Flutter SDK style
+    - unnecessary_getters_setters # Flutter SDK style
+    - unnecessary_new # Flutter SDK style
+    - unnecessary_null_aware_assignments # Flutter SDK style
+    - unnecessary_null_in_if_null_operators
+    - unnecessary_overrides # Flutter SDK style
+    - unnecessary_parenthesis # Flutter SDK style
+    - unnecessary_statements # Flutter SDK style
+    - unnecessary_this # Flutter SDK style
+    - unrelated_type_equality_checks
+    - use_rethrow_when_possible
+    - valid_regexps

lib/base/base_api.dart

@@ -1,15 +1,14 @@
-import 'package:http/http.dart' as http;
 import 'dart:convert';
-
 import 'dart:io';
 
+import 'package:http/http.dart' as http;
 import 'package:meta/meta.dart';
 
 class BaseApi {
-  final http.Client client;
-
   BaseApi({@required this.client});
 
+  final http.Client client;
+
   final String baseUrl = 'https://giv-api.herokuapp.com/';
 
   Future<http.Response> get(String url) =>

lib/base/base_material_app.dart

@@ -8,12 +8,12 @@ class BaseMaterialApp extends StatelessWidget {
   Widget build(BuildContext context) {
     return MaterialApp(
       debugShowCheckedModeBanner: false,
-      localizationsDelegates: [
-        const StringLocalizationsDelegate(),
+      localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
+        StringLocalizationsDelegate(),
         GlobalMaterialLocalizations.delegate,
         GlobalWidgetsLocalizations.delegate,
       ],
-      supportedLocales: AppLocales.supportedLocales,
+      supportedLocales: supportedLocales,
       home: Home(),
     );
   }

lib/base/dependency_provider.dart

@@ -13,17 +13,16 @@ class DependencyProvider extends InheritedWidget {
   final AppDependencies dependencies;
 
   static DependencyProvider of(BuildContext context) {
-    return context.inheritFromWidgetOfExactType(DependencyProvider)
-        as DependencyProvider;
+    return context.inheritFromWidgetOfExactType(DependencyProvider);
   }
 
   @override
-  bool updateShouldNotify(DependencyProvider old) => true;
+  bool updateShouldNotify(DependencyProvider oldWidget) => true;
 }
 
 class AppDependencies {
+  AppDependencies({this.loginBloc, this.homeBloc});
+
   final LoginBloc loginBloc;
   final HomeBloc homeBloc;
-
-  AppDependencies({this.loginBloc, this.homeBloc});
 }

lib/base/my_app.dart

@@ -3,10 +3,10 @@ import 'package:flutter_workshop/base/base_material_app.dart';
 import 'package:flutter_workshop/base/dependency_provider.dart';
 
 class MyApp extends StatefulWidget {
-  final AppDependencies dependencies;
-
   const MyApp({Key key, this.dependencies}) : super(key: key);
 
+  final AppDependencies dependencies;
+
   @override
   _MyAppState createState() => _MyAppState();
 }

lib/config/l10n.dart

@@ -2,12 +2,20 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_workshop/values/strings.dart';
 
+const Iterable<Locale> supportedLocales = <Locale>[
+  Locale('en'),
+  Locale('pt'),
+];
+
+List<String> get supportedLanguageCodes =>
+    supportedLocales.map((Locale locale) => locale.languageCode).toList();
+
 class StringLocalizationsDelegate extends LocalizationsDelegate<L10n> {
   const StringLocalizationsDelegate();
 
   @override
   bool isSupported(Locale locale) =>
-      AppLocales.supportedLanguageCodes.contains(locale.languageCode);
+      supportedLanguageCodes.contains(locale.languageCode);
 
   @override
   Future<L10n> load(Locale locale) => SynchronousFuture<L10n>(L10n(locale));
@@ -20,8 +28,8 @@ class L10n {
   L10n(this._locale);
 
   final Locale _locale;
-  final String defaultLanguageCode = AppLocales.supportedLanguageCodes.first;
-  static Map<String, Map<String, String>> _localizedValues = Strings().map;
+  final String defaultLanguageCode = supportedLanguageCodes.first;
+  final Map<String, Map<String, String>> _localizedValues = Strings().map;
 
   String _get(String key) {
     if (_localizedValues[key] == null) return key;
@@ -34,13 +42,3 @@ class L10n {
   static String getString(BuildContext context, String key) =>
       key == null ? null : Localizations.of<L10n>(context, L10n)._get(key);
 }
-
-class AppLocales {
-  static const supportedLocales = [
-    const Locale('en'),
-    const Locale('pt'),
-  ];
-
-  static List<String> get supportedLanguageCodes =>
-      supportedLocales.map((locale) => locale.languageCode).toList();
-}

lib/custom/custom_alert_dialog.dart

@@ -2,13 +2,6 @@ import 'package:flutter/material.dart';
 import 'package:flutter_workshop/config/l10n.dart';
 
 class CustomAlertDialog extends StatelessWidget {
-  final VoidCallback onConfirmed;
-  final String confirmationText;
-  final String cancellationText;
-  final String titleText;
-  final String contentText;
-  final bool hasCancelButton;
-
   const CustomAlertDialog(
       {Key key,
       this.onConfirmed,
@@ -19,10 +12,17 @@ class CustomAlertDialog extends StatelessWidget {
       this.hasCancelButton = false})
       : super(key: key);
 
+  final VoidCallback onConfirmed;
+  final String confirmationText;
+  final String cancellationText;
+  final String titleText;
+  final String contentText;
+  final bool hasCancelButton;
+
   @override
   Widget build(BuildContext context) {
-    final title = titleText == null ? null : Text(titleText);
-    final content = contentText == null ? null : Text(contentText);
+    final Text title = titleText == null ? null : Text(titleText);
+    final Text content = contentText == null ? null : Text(contentText);
 
     return AlertDialog(
       title: title,
@@ -37,12 +37,12 @@ class CustomAlertDialog extends StatelessWidget {
     );
   }
 
-  Widget _cancelButton(context) => FlatButton(
+  Widget _cancelButton(BuildContext context) => FlatButton(
         child: Text(
           cancellationText ?? L10n.getString(context, 'common_cancel'),
         ),
         onPressed: () => _closeDialog(context),
       );
 
-  _closeDialog(context) => Navigator.of(context).pop();
+  bool _closeDialog(BuildContext context) => Navigator.of(context).pop();
 }

lib/custom/custom_app_bar.dart

@@ -1,31 +1,35 @@
 import 'package:flutter/material.dart';
 
 class CustomAppBar extends StatelessWidget implements PreferredSizeWidget {
+  const CustomAppBar({Key key, this.actions, this.title}) : super(key: key);
+
   final List<Widget> actions;
   final String title;
 
-  const CustomAppBar({Key key, this.actions, this.title}) : super(key: key);
-
   @override
   Widget build(BuildContext context) {
-    final computedTitle = title == null ? '' : title;
+    final String computedTitle = title == null ? '' : title;
 
     return AppBar(
       brightness: Brightness.light,
       backgroundColor: Colors.white,
-      iconTheme: IconThemeData(color: Colors.grey),
-      title: Text(computedTitle, style: TextStyle(color: Colors.grey[800]),),
+      iconTheme: const IconThemeData(color: Colors.grey),
+      title: Text(
+        computedTitle,
+        style: TextStyle(color: Colors.grey[800]),
+      ),
       elevation: 0,
       actions: actions,
       bottom: CustomAppBarBottom(),
     );
   }
 
   @override
-  Size get preferredSize => Size.fromHeight(kToolbarHeight);
+  Size get preferredSize => const Size.fromHeight(kToolbarHeight);
 }
 
-class CustomAppBarBottom extends StatelessWidget implements PreferredSizeWidget {
+class CustomAppBarBottom extends StatelessWidget
+    implements PreferredSizeWidget {
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -35,6 +39,5 @@ class CustomAppBarBottom extends StatelessWidget implements PreferredSizeWidget
   }
 
   @override
-  Size get preferredSize => Size.fromHeight(1);
+  Size get preferredSize => const Size.fromHeight(1);
 }
-

lib/feature/detail/detail.dart

@@ -4,21 +4,21 @@ import 'package:flutter_workshop/model/donation/donation.dart';
 import 'package:flutter_workshop/model/user/user.dart';
 
 class Detail extends StatelessWidget {
-  final Donation donation;
-
   const Detail({Key key, this.donation}) : super(key: key);
 
+  final Donation donation;
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: CustomAppBar(),
+      appBar: const CustomAppBar(),
       body: _body(),
     );
   }
 
   Widget _body() {
     return Container(
-      padding: EdgeInsets.all(20),
+      padding: const EdgeInsets.all(20),
       child: ListView(
         children: <Widget>[
           _carousel(),
@@ -34,9 +34,9 @@ class Detail extends StatelessWidget {
   }
 
   Row _user(User user) {
-    final backgroundImage =
+    final ImageProvider backgroundImage =
         user.avatarUrl == null ? null : NetworkImage(user.avatarUrl);
-    final child =
+    final Widget child =
         user.avatarUrl == null ? Text(user.name[0].toUpperCase()) : null;
 
     return Row(
@@ -47,19 +47,13 @@ class Detail extends StatelessWidget {
           backgroundColor: Colors.blue,
           foregroundColor: Colors.white,
         ),
-        SizedBox(
-          width: 16,
-        ),
+        const SizedBox(width: 16),
         Text(user.name)
       ],
     );
   }
 
-  SizedBox _verticalMargin() {
-    return SizedBox(
-      height: 24,
-    );
-  }
+  SizedBox _verticalMargin() => const SizedBox(height: 24);
 
   Text _description() => Text(donation.description);
 
@@ -69,14 +63,14 @@ class Detail extends StatelessWidget {
       );
 
   Widget _carousel() {
-    final size = 300.0;
+    const double size = 300.0;
     return SizedBox(
       height: size,
       child: ListView.builder(
           scrollDirection: Axis.horizontal,
           itemCount: donation.images.length,
-          itemBuilder: (context, index) {
-            String url = donation.images[index].url;
+          itemBuilder: (BuildContext context, int index) {
+            final String url = donation.images[index].url;
             return _image(url, size);
           }),
     );