`RefreshIndicator`: Add an interactive example (#97254)

examples/api/lib/material/refresh_indicator/refresh_indicator.0.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flutter code sample for RefreshIndicator
+
+import 'package:flutter/material.dart';
+
+void main() => runApp(const MyApp());
+
+class MyApp extends StatelessWidget {
+  const MyApp({Key? key}) : super(key: key);
+
+  static const String _title = 'RefreshIndicator Sample';
+
+  @override
+  Widget build(BuildContext context) {
+    return const MaterialApp(
+      title: _title,
+      home: RefreshIndicatorExample(title: _title),
+    );
+  }
+}
+
+class RefreshIndicatorExample extends StatefulWidget {
+  const RefreshIndicatorExample({Key? key, required this.title}) : super(key: key);
+
+  final String title;
+
+  @override
+  State<RefreshIndicatorExample> createState() => _RefreshIndicatorExampleState();
+}
+
+class _RefreshIndicatorExampleState extends State<RefreshIndicatorExample> {
+  final GlobalKey<RefreshIndicatorState> _refreshIndicatorKey =
+    GlobalKey<RefreshIndicatorState>();
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(widget.title),
+      ),
+      body: RefreshIndicator(
+        key: _refreshIndicatorKey,
+        color: Colors.white,
+        backgroundColor: Colors.blue,
+        strokeWidth: 4.0,
+        onRefresh: () async {
+          // Replace this delay with the code to be executed during refresh
+          // and return a Future when code finishs execution.
+          return Future<void>.delayed(const Duration(seconds: 3));
+        },
+        // Pull from top to show refresh indicator.
+        child: ListView.builder(
+          itemCount: 25,
+          itemBuilder: (BuildContext context, int index) {
+            return ListTile(
+              title: Text('Item $index'),
+            );
+          },
+        ),
+      ),
+      floatingActionButton: FloatingActionButton.extended(
+        onPressed: () {
+          // Show refresh indicator programmatically on button tap.
+          _refreshIndicatorKey.currentState?.show();
+        },
+        icon: const Icon(Icons.refresh),
+        label: const Text('Show Indicator'),
+      ),
+    );
+  }
+}

examples/api/test/material/refresh_indicator/refresh_indicator.0_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_api_samples/material/refresh_indicator/refresh_indicator.0.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Trigger RefreshIndicator - Pull from top', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.MyApp(),
+    );
+
+    await tester.fling(find.text('Item 1'), const Offset(0.0, 300.0), 1000.0);
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1));
+    await tester.pump(const Duration(seconds: 1));
+    expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, lessThan(300.0));
+    await tester.pumpAndSettle(); // Advance pending time
+  });
+
+  testWidgets('Trigger RefreshIndicator - Button', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const example.MyApp(),
+    );
+
+    await tester.tap(find.byType(FloatingActionButton));
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1));
+    await tester.pump(const Duration(seconds: 1));
+    expect(tester.getCenter(find.byType(RefreshProgressIndicator)).dy, lessThan(300.0));
+    await tester.pumpAndSettle(); // Advance pending time
+  });
+}

packages/flutter/lib/src/material/refresh_indicator.dart

@@ -71,6 +71,12 @@ enum RefreshIndicatorTriggerMode {
 ///
 /// The trigger mode is configured by [RefreshIndicator.triggerMode].
 ///
+/// {@tool dartpad}
+/// This example shows how [RefreshIndicator] can be triggered in different ways.
+///
+/// ** See code in examples/api/lib/material/refresh_indicator/refresh_indicator.0.dart **
+/// {@end-tool}
+///
 /// ## Troubleshooting
 ///
 /// ### Refresh indicator does not show up