More work.

pkgs/flutter_http_example/lib/main.dart

@@ -7,13 +7,25 @@ import 'dart:convert';
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 import 'package:http/http.dart';
+import 'package:provider/provider.dart';
 
 import 'book.dart';
 import 'http_client_factory.dart'
     if (dart.library.html) 'http_client_factory_web.dart' as http_factory;
 
 void main() {
-  runWithClient(() => runApp(const BookSearchApp()), http_factory.httpClient);
+  // Some plugins may offer a way to inject a `package:http` `Client` so
+  // use `runWithClient` to control the `Client` that they use.
+  //
+  // `runWithClient` is not sufficient, however, because flutter tests do
+  // not preserve the `Zone` used as part of the `runWithClient`
+  // implementation. See https://github.com/flutter/flutter/issues/96939.
+  runWithClient(
+      () => runApp(Provider<Client>(
+          create: (_) => http_factory.httpClient(),
+          child: const BookSearchApp(),
+          dispose: (_, client) => client.close())),
+      http_factory.httpClient);
 }
 
 class BookSearchApp extends StatelessWidget {
@@ -38,24 +50,25 @@ class HomePage extends StatefulWidget {
 class _HomePageState extends State<HomePage> {
   List<Book>? _books;
   String? _lastQuery;
+  late Client _client;
 
   @override
   void initState() {
     super.initState();
+    _client = context.read<Client>();
   }
 
   // Get the list of books matching `query`.
   // The `get` call will automatically use the `client` configurated in `main`.
   Future<List<Book>> _findMatchingBooks(String query) async {
-    final response = await get(
+    final response = await _client.get(
       Uri.https(
         'www.googleapis.com',
         '/books/v1/volumes',
         {'q': query, 'maxResults': '1', 'printType': 'books'},
       ),
     );
 
-    print(utf8.decode(response.bodyBytes));
     final json = jsonDecode(utf8.decode(response.bodyBytes)) as Map;
     return Book.listFromJson(json);
   }

pkgs/flutter_http_example/pubspec.yaml

@@ -19,6 +19,7 @@ dependencies:
   flutter:
     sdk: flutter
   http: ^0.13.5
+  provider: ^6.0.5
 
 dev_dependencies:
   dart_flutter_team_lints: ^1.0.0

pkgs/flutter_http_example/test/widget_test.dart

@@ -3,58 +3,60 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:flutter/material.dart';
-import 'package:http/http.dart';
 import 'package:flutter_http_example/main.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart';
 import 'package:http/testing.dart';
+import 'package:provider/provider.dart';
 
 const _singleBookResponse = '''
 {
-  "kind": "books#volumes",
-  "totalItems": 2069,
   "items": [
     {
-      "kind": "books#volume",
-      "id": "gcnAEAAAQBAJ",
-      "etag": "8yZ12V0pNUI",
-      "selfLink": "https://www.googleapis.com/books/v1/volumes/gcnAEAAAQBAJ",
       "volumeInfo": {
         "title": "Flutter Cookbook",
-        "subtitle": "100+ step-by-step recipes for building cross...",
-        "authors": [
-          "Simone Alessandria"
-        ],
-        "publisher": "Packt Publishing Ltd",
-        "publishedDate": "2023-05-31",
         "description": "Write, test, and publish your web, desktop...",
-    }]
+        "imageLinks": {
+          "smallThumbnail": "http://books.google.com/books/content?id=gcnAEAAAQBAJ&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api"
+        }
+      }
+    }
+  ]
 }
 ''';
 
 void main() {
+  Widget app(Client client) =>
+      Provider<Client>(create: (_) => client, child: const BookSearchApp());
+
   testWidgets('Test initial load', (WidgetTester tester) async {
-    await tester.pumpWidget(const BookSearchApp());
+    final mockClient = MockClient(
+        (request) async => throw StateError('unexpected HTTP request'));
+
+    await tester.pumpWidget(app(mockClient));
 
     expect(find.text('Please enter a query'), findsOneWidget);
   });
 
   testWidgets('Test search', (WidgetTester tester) async {
     final mockClient = MockClient((request) async {
-      if (request.url.path != '/books/v1/volumes') {
+      if (request.url.path != '/books/v1/volumes' &&
+          request.url.queryParameters['q'] != 'Flutter') {
         return Response('', 404);
       }
       return Response(_singleBookResponse, 200);
     });
 
-    // `runWithClient` doesn't work because `pumpWidget` does not
-    // preserve the `Zone`.
-    await runWithClient(
-        () => tester.pumpWidget(const BookSearchApp()), () => mockClient);
-    await tester.enterText(find.byType(TextField), 'Flutter Cookbook');
+    await tester.pumpWidget(app(mockClient));
+    await tester.enterText(find.byType(TextField), 'Flutter');
     await tester.pump();
 
+    // The book title.
     expect(find.text('Flutter Cookbook'), findsOneWidget);
-    expect(find.text('Write, test, and publish your web, desktop...'),
+    // The book description.
+    expect(
+        find.text('Write, test, and publish your web, desktop...',
+            skipOffstage: false),
         findsOneWidget);
   });
 }