Update ExpansibleController in ExpansionTile didUpdateWidget (#173175)

Fixes https://github.com/flutter/flutter/issues/138916

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

@@ -94,7 +94,7 @@ typedef ExpansionTileController = ExpansibleController;
 /// {@end-tool}
 ///
 /// {@tool dartpad}
-/// This example demonstrates how an [ExpansionTileController] can be used to
+/// This example demonstrates how an [ExpansibleController] can be used to
 /// programmatically expand or collapse an [ExpansionTile].
 ///
 /// ** See code in examples/api/lib/material/expansion_tile/expansion_tile.1.dart **
@@ -398,7 +398,7 @@ class ExpansionTile extends StatefulWidget {
   /// In cases where control over the tile's state is needed from a callback
   /// triggered by a widget within the tile, [ExpansibleController.of] may be
   /// more convenient than supplying a controller.
-  final ExpansionTileController? controller;
+  final ExpansibleController? controller;
 
   /// {@macro flutter.material.ListTile.dense}
   final bool? dense;
@@ -497,7 +497,7 @@ class _ExpansionTileState extends State<ExpansionTile> {
   late Animation<Color?> _backgroundColor;
 
   late ExpansionTileThemeData _expansionTileTheme;
-  late ExpansionTileController _tileController;
+  late ExpansibleController _tileController;
   Timer? _timer;
   late Curve _curve;
   late Curve? _reverseCurve;
@@ -508,7 +508,7 @@ class _ExpansionTileState extends State<ExpansionTile> {
     super.initState();
     _curve = Curves.easeIn;
     _duration = _kExpand;
-    _tileController = widget.controller ?? ExpansionTileController();
+    _tileController = widget.controller ?? ExpansibleController();
     if (widget.initiallyExpanded) {
       _tileController.expand();
     }
@@ -718,6 +718,15 @@ class _ExpansionTileState extends State<ExpansionTile> {
       _updateAnimationDuration();
       _updateHeightFactorCurve();
     }
+    if (widget.controller != oldWidget.controller) {
+      _tileController.removeListener(_onExpansionChanged);
+      if (oldWidget.controller == null) {
+        _tileController.dispose();
+      }
+
+      _tileController = widget.controller ?? ExpansibleController();
+      _tileController.addListener(_onExpansionChanged);
+    }
   }
 
   @override

packages/flutter/lib/src/widgets/expansible.dart

@@ -329,6 +329,9 @@ class _ExpansibleState extends State<Expansible> with SingleTickerProviderStateM
     if (widget.controller != oldWidget.controller) {
       oldWidget.controller.removeListener(_toggleExpansion);
       widget.controller.addListener(_toggleExpansion);
+      if (oldWidget.controller.isExpanded != widget.controller.isExpanded) {
+        _toggleExpansion();
+      }
     }
   }
 

packages/flutter/test/material/expansion_tile_test.dart

@@ -1744,4 +1744,106 @@ void main() {
     final Offset offsetPlatform = tester.getTopLeft(platform);
     expect(offsetPlatform, const Offset(16.0, 17.0));
   });
+
+  testWidgets('ExpansionTile can accept a new controller', (WidgetTester tester) async {
+    final ExpansibleController controller1 = ExpansibleController();
+    final ExpansibleController controller2 = ExpansibleController();
+    addTearDown(() {
+      controller1.dispose();
+      controller2.dispose();
+    });
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: ExpansionTile(
+            controller: controller1,
+            title: const Text('Title'),
+            initiallyExpanded: true,
+            children: const <Widget>[Text('Child 0')],
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Child 0'), findsOne);
+    expect(controller1.isExpanded, isTrue);
+    controller1.collapse();
+    expect(controller1.isExpanded, isFalse);
+    await tester.pumpAndSettle();
+    expect(find.text('Child 0'), findsNothing);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: ExpansionTile(
+            controller: controller2,
+            title: const Text('Title'),
+            initiallyExpanded: true,
+            children: const <Widget>[Text('Child 0')],
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Child 0'), findsNothing);
+    controller2.expand();
+    expect(controller2.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Child 0'), findsOne);
+  });
+
+  testWidgets('ExpansionTile can accept a new controller with a different state', (
+    WidgetTester tester,
+  ) async {
+    final ExpansibleController controller1 = ExpansibleController();
+    final ExpansibleController controller2 = ExpansibleController();
+    addTearDown(() {
+      controller1.dispose();
+      controller2.dispose();
+    });
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: ExpansionTile(
+            controller: controller1,
+            title: const Text('Title'),
+            children: const <Widget>[Text('Child 0')],
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Child 0'), findsNothing);
+    expect(controller1.isExpanded, isFalse);
+    controller1.expand();
+    expect(controller1.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Child 0'), findsOne);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: ExpansionTile(
+            controller: controller2,
+            title: const Text('Title'),
+            children: const <Widget>[Text('Child 0')],
+          ),
+        ),
+      ),
+    );
+
+    await tester.pumpAndSettle();
+
+    expect(
+      find.text('Child 0'),
+      findsNothing,
+      reason: 'The widget should update to the state of the new controller',
+    );
+    controller2.expand();
+    expect(controller2.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Child 0'), findsOne);
+  });
 }

packages/flutter/test/widgets/expansible_test.dart

@@ -247,4 +247,120 @@ void main() {
 
     controller.dispose();
   });
+
+  testWidgets('ExpansionTile can accept a new controller', (WidgetTester tester) async {
+    final ExpansibleController controller1 = ExpansibleController();
+    final ExpansibleController controller2 = ExpansibleController();
+    addTearDown(() {
+      controller1.dispose();
+      controller2.dispose();
+    });
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Expansible(
+            controller: controller1,
+            headerBuilder: (_, _) => const Text('Header'),
+            bodyBuilder: (_, _) => const Text('Body'),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Body'), findsNothing);
+    expect(controller1.isExpanded, isFalse);
+
+    controller1.expand();
+    expect(controller1.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsOne);
+
+    controller1.collapse();
+    expect(controller1.isExpanded, isFalse);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsNothing);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Expansible(
+            controller: controller2,
+            headerBuilder: (_, _) => const Text('Header'),
+            bodyBuilder: (_, _) => const Text('Body'),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Body'), findsNothing);
+    expect(controller2.isExpanded, isFalse);
+
+    controller2.expand();
+    expect(controller2.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsOne);
+
+    controller2.collapse();
+    expect(controller2.isExpanded, isFalse);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsNothing);
+  });
+
+  testWidgets('Expansible can accept a new controller with a different state', (
+    WidgetTester tester,
+  ) async {
+    final ExpansibleController controller1 = ExpansibleController();
+    final ExpansibleController controller2 = ExpansibleController();
+    addTearDown(() {
+      controller1.dispose();
+      controller2.dispose();
+    });
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Expansible(
+            controller: controller1,
+            headerBuilder: (_, _) => const Text('Header'),
+            bodyBuilder: (_, _) => const Text('Body'),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Body'), findsNothing);
+    expect(controller1.isExpanded, isFalse);
+
+    controller1.expand();
+    expect(controller1.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsOne);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Expansible(
+            controller: controller2,
+            headerBuilder: (_, _) => const Text('Header'),
+            bodyBuilder: (_, _) => const Text('Body'),
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+
+    expect(controller2.isExpanded, isFalse);
+    expect(find.text('Body'), findsNothing);
+
+    controller2.expand();
+    expect(controller2.isExpanded, isTrue);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsOne);
+
+    controller2.collapse();
+    expect(controller2.isExpanded, isFalse);
+    await tester.pumpAndSettle();
+    expect(find.text('Body'), findsNothing);
+  });
 }