Make font semibold when isDefaultAction is true in CupertinoDialogAction (#31308)

Make font semibold when isDefaultAction is true in CupertinoDialogAction

packages/flutter/lib/src/cupertino/dialog.dart

@@ -1043,7 +1043,9 @@ class CupertinoDialogAction extends StatelessWidget {
     this.isDestructiveAction = false,
     this.textStyle,
     @required this.child,
-  }) : assert(child != null);
+  }) : assert(child != null),
+       assert(isDefaultAction != null),
+       assert(isDestructiveAction != null);
 
   /// The callback that is called when the button is tapped or otherwise
   /// activated.
@@ -1054,11 +1056,15 @@ class CupertinoDialogAction extends StatelessWidget {
   /// Set to true if button is the default choice in the dialog.
   ///
   /// Default buttons are bold.
+  ///
+  /// This parameters defaults to false and cannot be null.
   final bool isDefaultAction;
 
   /// Whether this action destroys an object.
   ///
   /// For example, an action that deletes an email is destructive.
+  ///
+  /// Defaults to false and cannot be null.
   final bool isDestructiveAction;
 
   /// [TextStyle] to apply to any text that appears in this button.
@@ -1149,6 +1155,10 @@ class CupertinoDialogAction extends StatelessWidget {
     TextStyle style = _kCupertinoDialogActionStyle;
     style = style.merge(textStyle);
 
+    if (isDefaultAction) {
+      style = style.copyWith(fontWeight: FontWeight.w600);
+    }
+
     if (isDestructiveAction) {
       style = style.copyWith(color: CupertinoColors.destructiveRed);
     }

packages/flutter/test/cupertino/dialog_test.dart

@@ -52,7 +52,7 @@ void main() {
     expect(find.text('Delete'), findsNothing);
   });
 
-  testWidgets('Dialog destructive action styles', (WidgetTester tester) async {
+  testWidgets('Dialog destructive action style', (WidgetTester tester) async {
     await tester.pumpWidget(boilerplate(const CupertinoDialogAction(
       isDestructiveAction: true,
       child: Text('Ok'),
@@ -60,8 +60,7 @@ void main() {
 
     final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
 
-    expect(widget.style.color.red, greaterThan(widget.style.color.blue));
-    expect(widget.style.color.alpha, lessThan(255));
+    expect(widget.style.color.withAlpha(255), CupertinoColors.destructiveRed);
   });
 
   testWidgets('Has semantic annotations', (WidgetTester tester) async {
@@ -132,7 +131,7 @@ void main() {
     semantics.dispose();
   });
 
-  testWidgets('Dialog default action styles', (WidgetTester tester) async {
+  testWidgets('Dialog default action style', (WidgetTester tester) async {
     await tester.pumpWidget(boilerplate(const CupertinoDialogAction(
       isDefaultAction: true,
       child: Text('Ok'),
@@ -140,10 +139,10 @@ void main() {
 
     final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
 
-    expect(widget.style.fontWeight, equals(FontWeight.w400));
+    expect(widget.style.fontWeight, equals(FontWeight.w600));
   });
 
-  testWidgets('Default and destructive style', (WidgetTester tester) async {
+  testWidgets('Dialog default and destructive action styles', (WidgetTester tester) async {
     await tester.pumpWidget(boilerplate(const CupertinoDialogAction(
       isDefaultAction: true,
       isDestructiveAction: true,
@@ -152,8 +151,30 @@ void main() {
 
     final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
 
-    expect(widget.style.fontWeight, equals(FontWeight.w400));
-    expect(widget.style.color.red, greaterThan(widget.style.color.blue));
+    expect(widget.style.color.withAlpha(255), CupertinoColors.destructiveRed);
+    expect(widget.style.fontWeight, equals(FontWeight.w600));
+  });
+
+  testWidgets('Dialog disabled action style', (WidgetTester tester) async {
+    await tester.pumpWidget(boilerplate(const CupertinoDialogAction(
+      child: Text('Ok'),
+    )));
+
+    final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
+
+    expect(widget.style.color.opacity, greaterThanOrEqualTo(127 / 255));
+    expect(widget.style.color.opacity, lessThanOrEqualTo(128 / 255));
+  });
+
+  testWidgets('Dialog enabled action style', (WidgetTester tester) async {
+    await tester.pumpWidget(boilerplate(CupertinoDialogAction(
+      child: const Text('Ok'),
+      onPressed: () {},
+    )));
+
+    final DefaultTextStyle widget = tester.widget(find.byType(DefaultTextStyle));
+
+    expect(widget.style.color.opacity, equals(1.0));
   });
 
   testWidgets('Message is scrollable, has correct padding with large text sizes', (WidgetTester tester) async {