Add more tests to slider to avoid future breakages (#98772)

packages/flutter/test/material/value_indicating_slider_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.
+
+// This file is run as part of a reduced test set in CI on Mac and Windows
+// machines.
+@Tags(<String>['reduced-test-set'])
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Slider value indicator', (WidgetTester tester) async {
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0,
+    );
+
+    await _pressStartThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_start_text_scale_1_width_0'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0.5,
+    );
+
+    await _pressMiddleThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_middle_text_scale_1_width_0'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 1,
+    );
+
+    await _pressEndThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_end_text_scale_1_width_0'),
+    );
+  });
+
+  testWidgets('Slider value indicator wide text', (WidgetTester tester) async {
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0,
+      decimalCount: 5,
+    );
+
+    await _pressStartThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_start_text_scale_1_width_5'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0.5,
+      decimalCount: 5,
+    );
+
+    await _pressMiddleThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_middle_text_scale_1_width_5'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 1,
+      decimalCount: 5,
+    );
+
+    await _pressEndThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_end_text_scale_1_width_5'),
+    );
+  });
+
+  testWidgets('Slider value indicator large text scale', (WidgetTester tester) async {
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0,
+      textScale: 3,
+    );
+
+    await _pressStartThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_start_text_scale_4_width_0'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0.5,
+      textScale: 3,
+    );
+
+    await _pressMiddleThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_middle_text_scale_4_width_0'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 1,
+      textScale: 3,
+    );
+
+    await _pressEndThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_end_text_scale_4_width_0'),
+    );
+  });
+
+  testWidgets('Slider value indicator large text scale and wide text',
+      (WidgetTester tester) async {
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0,
+      textScale: 3,
+      decimalCount: 5,
+    );
+
+    await _pressStartThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_start_text_scale_4_width_5'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 0.5,
+      textScale: 3,
+      decimalCount: 5,
+    );
+
+    await _pressMiddleThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_middle_text_scale_4_width_5'),
+    );
+
+    await _buildValueIndicatorStaticSlider(
+      tester,
+      value: 1,
+      textScale: 3,
+      decimalCount: 5,
+    );
+
+    await _pressEndThumb(tester);
+
+    await expectLater(
+      find.byType(MaterialApp),
+      matchesGoldenFile('slider_end_text_scale_4_width_5'),
+    );
+  });
+}
+
+Future<void> _pressStartThumb(WidgetTester tester) async {
+  final Offset bottomLeft = tester.getBottomLeft(find.byType(Slider));
+  final Offset topLeft = tester.getTopLeft(find.byType(Slider));
+  final Offset left = (bottomLeft + topLeft) / 2;
+  final Offset start = left + const Offset(24, 0);
+  await tester.startGesture(start);
+  await tester.pumpAndSettle();
+}
+
+Future<void> _pressMiddleThumb(WidgetTester tester) async {
+  await tester.press(find.byType(Slider));
+  await tester.pumpAndSettle();
+}
+
+Future<void> _pressEndThumb(WidgetTester tester) async {
+  final Offset bottomRight = tester.getBottomRight(find.byType(Slider));
+  final Offset topRight = tester.getTopRight(find.byType(Slider));
+  final Offset right = (bottomRight + topRight) / 2;
+  final Offset start = right - const Offset(24, 0);
+  await tester.startGesture(start);
+  await tester.pumpAndSettle();
+}
+
+Future<void> _buildValueIndicatorStaticSlider(
+  WidgetTester tester, {
+  required double value,
+  double textScale = 1.0,
+  int decimalCount = 0,
+}) async {
+  await tester.pumpWidget(
+    MaterialApp(
+      home: Scaffold(
+        body: Builder(
+          builder: (BuildContext context) {
+            return Center(
+              child: MediaQuery(
+                data: MediaQueryData(textScaleFactor: textScale),
+                child: SliderTheme(
+                  data: Theme.of(context).sliderTheme.copyWith(
+                    showValueIndicator: ShowValueIndicator.always,
+                  ),
+                  child: Slider(
+                    value: value,
+                    label: value.toStringAsFixed(decimalCount),
+                    onChanged: (double newValue) {},
+                  ),
+                ),
+              ),
+            );
+          },
+        ),
+      ),
+    ),
+  );
+}