Create a flutter example application that uses multiple client implementations (#1040)

Author: brianquinlan

.github/workflows/dart.yml

@@ -14,3 +14,4 @@ and the browser.
 | [http_client_conformance_tests](pkgs/http_client_conformance_tests/) | A library that tests whether implementations of package:http's `Client` class behave as expected. | |
 | [cronet_http](pkgs/cronet_http/) | An Android Flutter plugin that provides access to the [Cronet](https://developer.android.com/guide/topics/connectivity/cronet/reference/org/chromium/net/package-summary) HTTP client. | [![pub package](https://img.shields.io/pub/v/cronet_http.svg)](https://pub.dev/packages/cronet_http) |
 | [cupertino_http](pkgs/cupertino_http/) | A macOS/iOS Flutter plugin that provides access to the [Foundation URL Loading System](https://developer.apple.com/documentation/foundation/url_loading_system). | [![pub package](https://img.shields.io/pub/v/cupertino_http.svg)](https://pub.dev/packages/cupertino_http) |
+| [flutter_http_example](pkgs/flutter_http_example/) | An Flutter app that demonstrates how to configure and use `package:http`. | — |

README.md

@@ -1,4 +1,4 @@
-// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
@@ -12,20 +12,16 @@ class Book {
   static List<Book> listFromJson(Map<dynamic, dynamic> json) {
     final books = <Book>[];
 
-    if (json['items'] is List<dynamic>) {
-      final items = (json['items'] as List).cast<Map<String, Object?>>();
-
+    if (json['items'] case final List<dynamic> items) {
       for (final item in items) {
-        if (item.containsKey('volumeInfo')) {
-          final volumeInfo = item['volumeInfo'] as Map;
-          if (volumeInfo['title'] is String &&
-              volumeInfo['description'] is String &&
-              volumeInfo['imageLinks'] is Map &&
-              (volumeInfo['imageLinks'] as Map)['smallThumbnail'] is String) {
-            books.add(Book(
-                volumeInfo['title'] as String,
-                volumeInfo['description'] as String,
-                (volumeInfo['imageLinks'] as Map)['smallThumbnail'] as String));
+        if (item case {'volumeInfo': final Map<dynamic, dynamic> volumeInfo}) {
+          if (volumeInfo
+              case {
+                'title': final String title,
+                'description': final String description,
+                'imageLinks': {'smallThumbnail': final String thumbnail}
+              }) {
+            books.add(Book(title, description, thumbnail));
           }
         }
       }

pkgs/cronet_http/example/lib/book.dart

@@ -43,6 +43,7 @@ class HomePage extends StatefulWidget {
 
 class _HomePageState extends State<HomePage> {
   List<Book>? _books;
+  String? _lastQuery;
 
   @override
   void initState() {
@@ -65,6 +66,7 @@ class _HomePageState extends State<HomePage> {
   }
 
   void _runSearch(String query) async {
+    _lastQuery = query;
     if (query.isEmpty) {
       setState(() {
         _books = null;
@@ -73,6 +75,9 @@ class _HomePageState extends State<HomePage> {
     }
 
     final books = await _findMatchingBooks(query);
+    // Avoid the situation where a slow-running query finishes late and
+    // replaces newer search results.
+    if (query != _lastQuery) return;
     setState(() {
       _books = books;
     });
@@ -127,7 +132,8 @@ class _BookListState extends State<BookList> {
             leading: CachedNetworkImage(
                 placeholder: (context, url) =>
                     const CircularProgressIndicator(),
-                imageUrl: widget.books[index].imageUrl),
+                imageUrl:
+                    widget.books[index].imageUrl.replaceFirst('http', 'https')),
             title: Text(widget.books[index].title),
             subtitle: Text(widget.books[index].description),
           ),

pkgs/cronet_http/example/lib/main.dart

@@ -4,7 +4,7 @@ description: Demonstrates how to use the cronet_http plugin.
 publish_to: 'none'
 
 environment:
-  sdk: ">=2.19.0 <3.0.0"
+  sdk: "^3.0.0"
 
 dependencies:
   cached_network_image: ^3.2.3

pkgs/cronet_http/example/pubspec.yaml

@@ -12,20 +12,16 @@ class Book {
   static List<Book> listFromJson(Map<dynamic, dynamic> json) {
     final books = <Book>[];
 
-    if (json['items'] is List<dynamic>) {
-      final items = (json['items'] as List).cast<Map<String, Object?>>();
-
+    if (json['items'] case final List<dynamic> items) {
       for (final item in items) {
-        if (item.containsKey('volumeInfo')) {
-          final volumeInfo = item['volumeInfo'] as Map;
-          if (volumeInfo['title'] is String &&
-              volumeInfo['description'] is String &&
-              volumeInfo['imageLinks'] is Map &&
-              (volumeInfo['imageLinks'] as Map)['smallThumbnail'] is String) {
-            books.add(Book(
-                volumeInfo['title'] as String,
-                volumeInfo['description'] as String,
-                (volumeInfo['imageLinks'] as Map)['smallThumbnail'] as String));
+        if (item case {'volumeInfo': final Map<dynamic, dynamic> volumeInfo}) {
+          if (volumeInfo
+              case {
+                'title': final String title,
+                'description': final String description,
+                'imageLinks': {'smallThumbnail': final String thumbnail}
+              }) {
+            books.add(Book(title, description, thumbnail));
           }
         }
       }

pkgs/cupertino_http/example/lib/book.dart

@@ -41,6 +41,7 @@ class HomePage extends StatefulWidget {
 
 class _HomePageState extends State<HomePage> {
   List<Book>? _books;
+  String? _lastQuery;
 
   @override
   void initState() {
@@ -63,6 +64,7 @@ class _HomePageState extends State<HomePage> {
   }
 
   void _runSearch(String query) async {
+    _lastQuery = query;
     if (query.isEmpty) {
       setState(() {
         _books = null;
@@ -71,6 +73,9 @@ class _HomePageState extends State<HomePage> {
     }
 
     final books = await _findMatchingBooks(query);
+    // Avoid the situation where a slow-running query finishes late and
+    // replaces newer search results.
+    if (query != _lastQuery) return;
     setState(() {
       _books = books;
     });

pkgs/cupertino_http/example/lib/main.dart

@@ -0,0 +1,44 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.buildlog/
+.history
+.svn/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release

pkgs/flutter_http_example/.gitignore

@@ -0,0 +1,45 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: "367f9ea16bfae1ca451b9cc27c1366870b187ae2"
+  channel: "stable"
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+    - platform: android
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+    - platform: ios
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+    - platform: linux
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+    - platform: macos
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+    - platform: web
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+    - platform: windows
+      create_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+      base_revision: 367f9ea16bfae1ca451b9cc27c1366870b187ae2
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'

pkgs/flutter_http_example/.metadata

@@ -0,0 +1,43 @@
+# flutter_http_example
+
+A Flutter sample app that illustrates how to configure and use
+[`package:http`](https://pub.dev/packages/http).
+
+## Goals for this sample
+
+* Provide you with example code for using `package:http` in Flutter,
+  including:
+
+    * configuration for multiple platforms.
+    * using `runWithClient` and `package:provider` to pass `Client`s through
+      an application.
+    * writing tests using `MockClient`.
+
+## The important bits
+
+### `http_client_factory.dart`
+
+This library used to create `package:http` `Client`s when the app is run inside
+the Dart virtual machine, meaning all platforms except the web browser.
+
+### `http_client_factory_web.dart`
+
+This library used to create `package:http` `Client`s when the app is run inside
+a web browser.
+
+Web configuration must be done in a seperate library because Dart code cannot
+import `dart:ffi` or `dart:io` when run in a web browser.
+
+### `main.dart`
+
+This library demonstrates how to:
+
+* import `http_client_factory.dart` or `http_client_factory_web.dart`,
+  depending on whether we are targeting the web browser or not.
+* share a `package:http` `Client` by using `runWithClient` and
+  `package:provider`.
+* call `package:http` functions.
+
+### `widget_test.dart`
+
+This library demonstrates how to construct tests using `MockClient`.