Setting icon color to first ListTile in ExpansionTile. Fixes #23053 (#23118)

AUTHORS

@@ -28,6 +28,7 @@ Christian Mürtz <teraarts@t-online.de>
 Lukasz Piliszczuk <lukasz@intheloup.io>
 Felix Schmidt <felix.free@gmx.de>
 Artur Rymarz <artur.rymarz@gmail.com>
+Chema Molins <chemamolins@gmail.com>
 Stefan Mitev <mr.mitew@gmail.com>
 Jasper van Riet <jaspervanriet@gmail.com>
 Mattijs Fuijkschot <mattijs.fuijkschot@gmail.com>

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

@@ -142,7 +142,6 @@ class _ExpansionTileState extends State<ExpansionTile> with SingleTickerProvider
 
   Widget _buildChildren(BuildContext context, Widget child) {
     final Color borderSideColor = _borderColor.value ?? Colors.transparent;
-    final Color titleColor = _headerColor.value;
 
     return Container(
       decoration: BoxDecoration(
@@ -155,15 +154,13 @@ class _ExpansionTileState extends State<ExpansionTile> with SingleTickerProvider
       child: Column(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
-          IconTheme.merge(
-            data: IconThemeData(color: _iconColor.value),
+          ListTileTheme.merge(
+            iconColor: _iconColor.value,
+            textColor: _headerColor.value,
             child: ListTile(
               onTap: _handleTap,
               leading: widget.leading,
-              title: DefaultTextStyle(
-                style: Theme.of(context).textTheme.subhead.copyWith(color: titleColor),
-                child: widget.title,
-              ),
+              title: widget.title,
               trailing: widget.trailing ?? RotationTransition(
                 turns: _iconTurns,
                 child: const Icon(Icons.expand_more),

packages/flutter/test/material/expansion_tile_test.dart

@@ -6,8 +6,47 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/material.dart';
 
+class TestIcon extends StatefulWidget {
+  const TestIcon({Key key}) : super(key: key);
+
+  @override
+  TestIconState createState() => TestIconState();
+}
+
+class TestIconState extends State<TestIcon> {
+  IconThemeData iconTheme;
+
+  @override
+  Widget build(BuildContext context) {
+    iconTheme = IconTheme.of(context);
+    return const Icon(Icons.expand_more);
+  }
+}
+
+class TestText extends StatefulWidget {
+  const TestText(this.text, {Key key}) : super(key: key);
+
+  final String text;
+
+  @override
+  TestTextState createState() => TestTextState();
+}
+
+class TestTextState extends State<TestText> {
+  TextStyle textStyle;
+
+  @override
+  Widget build(BuildContext context) {
+    textStyle = DefaultTextStyle.of(context).style;
+    return Text(widget.text);
+  }
+}
+
 void main() {
   const Color _dividerColor = Color(0x1f333333);
+  const Color _accentColor = Colors.blueAccent;
+  const Color _unselectedWidgetColor = Colors.black54;
+  const Color _headerColor = Colors.black45;
 
   testWidgets('ExpansionTile initial state', (WidgetTester tester) async {
     final Key topKey = UniqueKey();
@@ -116,4 +155,64 @@ void main() {
     expect(collapsedContainerDecoration.border.top.color, _dividerColor);
     expect(collapsedContainerDecoration.border.bottom.color, _dividerColor);
   });
+
+  testWidgets('ListTileTheme', (WidgetTester tester) async {
+    final Key expandedTitleKey = UniqueKey();
+    final Key collapsedTitleKey = UniqueKey();
+    final Key expandedIconKey = UniqueKey();
+    final Key collapsedIconKey = UniqueKey();
+
+    await tester.pumpWidget(
+      MaterialApp(
+        theme: ThemeData(
+          platform: TargetPlatform.iOS,
+          accentColor: _accentColor,
+          unselectedWidgetColor: _unselectedWidgetColor,
+          textTheme: const TextTheme(subhead: TextStyle(color: _headerColor)),
+        ),
+        home: Material(
+          child: SingleChildScrollView(
+            child: Column(
+              children: <Widget>[
+                const ListTile(title: Text('Top')),
+                ExpansionTile(
+                  initiallyExpanded: true,
+                  title: TestText('Expanded', key: expandedTitleKey),
+                  backgroundColor: Colors.red,
+                  children: const <Widget>[ListTile(title: Text('0'))],
+                  trailing: TestIcon(key: expandedIconKey),
+                ),
+                ExpansionTile(
+                  initiallyExpanded: false,
+                  title: TestText('Collapsed', key: collapsedTitleKey),
+                  children: const <Widget>[ListTile(title: Text('0'))],
+                  trailing: TestIcon(key: collapsedIconKey),
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+
+    Color iconColor(Key key) => tester.state<TestIconState>(find.byKey(key)).iconTheme.color;
+    Color textColor(Key key) => tester.state<TestTextState>(find.byKey(key)).textStyle.color;
+
+    expect(textColor(expandedTitleKey), _accentColor);
+    expect(textColor(collapsedTitleKey), _headerColor);
+    expect(iconColor(expandedIconKey), _accentColor);
+    expect(iconColor(collapsedIconKey), _unselectedWidgetColor);
+
+    // Tap both tiles to change their state: collapse and extend respectively
+    await tester.tap(find.text('Expanded'));
+    await tester.tap(find.text('Collapsed'));
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 1));
+    await tester.pump(const Duration(seconds: 1));
+
+    expect(textColor(expandedTitleKey), _headerColor);
+    expect(textColor(collapsedTitleKey), _accentColor);
+    expect(iconColor(expandedIconKey), _unselectedWidgetColor);
+    expect(iconColor(collapsedIconKey), _accentColor);
+  });
 }