Fix a `Slider` widget accessibility bug (#102129)

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

@@ -285,7 +285,9 @@ class RangeSlider extends StatefulWidget {
   /// If null, the slider is continuous.
   final int? divisions;
 
-  /// Labels to show as text in the [SliderThemeData.rangeValueIndicatorShape].
+  /// Labels to show as text in the [SliderThemeData.rangeValueIndicatorShape]
+  /// when the slider is active and [SliderThemeData.showValueIndicator]
+  /// is satisfied.
   ///
   /// There are two labels: one for the start thumb and one for the end thumb.
   ///
@@ -1491,7 +1493,6 @@ class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMix
     double value,
     double increasedValue,
     double decreasedValue,
-    String? label,
     VoidCallback increaseAction,
     VoidCallback decreaseAction,
   ) {
@@ -1503,7 +1504,7 @@ class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMix
       config.onIncrease = increaseAction;
       config.onDecrease = decreaseAction;
     }
-    config.label = label ?? '';
+
     if (semanticFormatterCallback != null) {
       config.value = semanticFormatterCallback!(_state._lerp(value));
       config.increasedValue = semanticFormatterCallback!(_state._lerp(increasedValue));
@@ -1529,7 +1530,6 @@ class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMix
       values.start,
       _increasedStartValue,
       _decreasedStartValue,
-      labels?.start,
       _increaseStartAction,
       _decreaseStartAction,
     );
@@ -1537,7 +1537,6 @@ class _RenderRangeSlider extends RenderBox with RelayoutWhenSystemFontsChangeMix
       values.end,
       _increasedEndValue,
       _decreasedEndValue,
-      labels?.end,
       _increaseEndAction,
       _decreaseEndAction,
     );

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

@@ -317,7 +317,8 @@ class Slider extends StatefulWidget {
   /// If null, the slider is continuous.
   final int? divisions;
 
-  /// A label to show above the slider when the slider is active.
+  /// A label to show above the slider when the slider is active and
+  /// [SliderThemeData.showValueIndicator] is satisfied.
   ///
   /// It is used to display the value of a discrete slider, and it is displayed
   /// as part of the value indicator shape.
@@ -1506,7 +1507,7 @@ class _RenderSlider extends RenderBox with RelayoutWhenSystemFontsChangeMixin {
       config.onIncrease = increaseAction;
       config.onDecrease = decreaseAction;
     }
-    config.label = _label ?? '';
+
     if (semanticFormatterCallback != null) {
       config.value = semanticFormatterCallback!(_state._lerp(value));
       config.increasedValue = semanticFormatterCallback!(_state._lerp((value + _semanticActionUnit).clamp(0.0, 1.0)));

packages/flutter/test/material/range_slider_test.dart

@@ -1681,6 +1681,65 @@ void main() {
     );
   });
 
+  // Regression test for https://github.com/flutter/flutter/issues/101868
+  testWidgets('RangeSlider.label info should not write to semantic node', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Theme(
+          data: ThemeData.light(),
+          child: Directionality(
+            textDirection: TextDirection.ltr,
+            child: Material(
+              child: RangeSlider(
+                values: const RangeValues(10.0, 12.0),
+                max: 100.0,
+                onChanged: (RangeValues v) { },
+                labels: const RangeLabels('Begin', 'End'),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.pumpAndSettle();
+
+    expect(
+      tester.getSemantics(find.byType(RangeSlider)),
+      matchesSemantics(
+        scopesRoute: true,
+        children:<Matcher>[
+          matchesSemantics(
+            children:  <Matcher>[
+              matchesSemantics(
+                isEnabled: true,
+                isSlider: true,
+                hasEnabledState: true,
+                hasIncreaseAction: true,
+                hasDecreaseAction: true,
+                value: '10%',
+                increasedValue: '10%',
+                decreasedValue: '5%',
+                label: ''
+              ),
+              matchesSemantics(
+                isEnabled: true,
+                isSlider: true,
+                hasEnabledState: true,
+                hasIncreaseAction: true,
+                hasDecreaseAction: true,
+                value: '12%',
+                increasedValue: '17%',
+                decreasedValue: '12%',
+                label: ''
+              ),
+            ],
+          ),
+        ],
+      ),
+    );
+  });
+
   testWidgets('Range Slider Semantics', (WidgetTester tester) async {
     await tester.pumpWidget(
       MaterialApp(

packages/flutter/test/material/slider_test.dart

@@ -1816,6 +1816,66 @@ void main() {
     semantics.dispose();
   });
 
+  // Regression test for https://github.com/flutter/flutter/issues/101868
+  testWidgets('Slider.label info should not write to semantic node', (WidgetTester tester) async {
+    final SemanticsTester semantics = SemanticsTester(tester);
+
+    await tester.pumpWidget(MaterialApp(
+      home: Directionality(
+        textDirection: TextDirection.ltr,
+        child: Material(
+          child: Slider(
+            value: 40.0,
+            max: 200.0,
+            divisions: 10,
+            semanticFormatterCallback: (double value) => value.round().toString(),
+            onChanged: (double v) { },
+            label: 'Bingo',
+          ),
+        ),
+      ),
+    ));
+
+    expect(
+      semantics,
+      hasSemantics(
+        TestSemantics.root(
+          children: <TestSemantics>[
+            TestSemantics(
+              id: 1,
+              textDirection: TextDirection.ltr,
+              children: <TestSemantics>[
+                TestSemantics(
+                  id: 2,
+                  children: <TestSemantics>[
+                    TestSemantics(
+                      id: 3,
+                      flags: <SemanticsFlag>[SemanticsFlag.scopesRoute],
+                      children: <TestSemantics>[
+                        TestSemantics(
+                          id: 4,
+                          flags: <SemanticsFlag>[SemanticsFlag.hasEnabledState, SemanticsFlag.isEnabled, SemanticsFlag.isFocusable, SemanticsFlag.isSlider],
+                          actions: <SemanticsAction>[SemanticsAction.increase, SemanticsAction.decrease],
+                          value: '40',
+                          increasedValue: '60',
+                          decreasedValue: '20',
+                          textDirection: TextDirection.ltr,
+                        ),
+                      ],
+                    ),
+                  ],
+                ),
+              ],
+            ),
+          ],
+        ),
+        ignoreRect: true,
+        ignoreTransform: true,
+      ),
+    );
+    semantics.dispose();
+  });
+
   testWidgets('Slider is focusable and has correct focus color', (WidgetTester tester) async {
     final FocusNode focusNode = FocusNode(debugLabel: 'Slider');
     tester.binding.focusManager.highlightStrategy = FocusHighlightStrategy.alwaysTraditional;