[Reland] - Update `DialogTheme` tests for M2/M3 (#130711)

This relands https://github.com/flutter/flutter/pull/130414 (which was reverted in https://github.com/flutter/flutter/pull/130578)

packages/flutter/test/material/dialog_theme_test.dart

@@ -165,7 +165,31 @@ void main() {
     expect(bottomLeft.dy, 576.0);
   });
 
-  testWidgets('Dialog alignment takes priority over theme', (WidgetTester tester) async {
+  testWidgets('Material3 - Dialog alignment takes priority over theme', (WidgetTester tester) async {
+    const AlertDialog dialog = AlertDialog(
+      title: Text('Title'),
+      actions: <Widget>[ ],
+      alignment: Alignment.topRight,
+    );
+    final ThemeData theme = ThemeData(
+      useMaterial3: true,
+      dialogTheme: const DialogTheme(alignment: Alignment.bottomLeft),
+    );
+
+    await tester.pumpWidget(
+      _appWithDialog(tester, dialog, theme: theme),
+    );
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    final Offset bottomLeft = tester.getBottomLeft(
+      find.descendant(of: find.byType(Dialog), matching: find.byType(Material)),
+    );
+    expect(bottomLeft.dx, 480.0);
+    expect(bottomLeft.dy, 124.0);
+  });
+
+  testWidgets('Material2 - Dialog alignment takes priority over theme', (WidgetTester tester) async {
     const AlertDialog dialog = AlertDialog(
       title: Text('Title'),
       actions: <Widget>[ ],
@@ -186,7 +210,29 @@ void main() {
     expect(bottomLeft.dy, 104.0);
   });
 
-  testWidgets('Custom dialog shape matches golden', (WidgetTester tester) async {
+  testWidgets('Material3 - Custom dialog shape matches golden', (WidgetTester tester) async {
+    const RoundedRectangleBorder customBorder =
+      RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(16.0)));
+    const AlertDialog dialog = AlertDialog(
+      title: Text('Title'),
+      actions: <Widget>[ ],
+    );
+    final ThemeData theme = ThemeData(
+      useMaterial3: true,
+      dialogTheme: const DialogTheme(shape: customBorder),
+    );
+
+    await tester.pumpWidget(_appWithDialog(tester, dialog, theme: theme));
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    await expectLater(
+      find.byKey(_painterKey),
+      matchesGoldenFile('m3_dialog_theme.dialog_with_custom_border.png'),
+    );
+  });
+
+  testWidgets('Material2 - Custom dialog shape matches golden', (WidgetTester tester) async {
     const RoundedRectangleBorder customBorder =
       RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(16.0)));
     const AlertDialog dialog = AlertDialog(
@@ -201,7 +247,7 @@ void main() {
 
     await expectLater(
       find.byKey(_painterKey),
-      matchesGoldenFile('dialog_theme.dialog_with_custom_border.png'),
+      matchesGoldenFile('m2_dialog_theme.dialog_with_custom_border.png'),
     );
   });
 
@@ -246,9 +292,8 @@ void main() {
     expect(text.text.style!.color, dialogThemeColor);
   });
 
-  testWidgets('Custom Icon Color - Theme - lowest preference', (WidgetTester tester) async {
-    const Color iconThemeColor = Colors.yellow;
-    final ThemeData theme = ThemeData(useMaterial3: false, iconTheme: const IconThemeData(color: iconThemeColor));
+  testWidgets('Material3 - Custom Icon Color - Theme - lowest preference', (WidgetTester tester) async {
+    final ThemeData theme = ThemeData(useMaterial3: true);
     const AlertDialog dialog = AlertDialog(
       icon: Icon(Icons.ac_unit),
       actions: <Widget>[ ],
@@ -260,11 +305,12 @@ void main() {
 
     // first is Text('X')
     final RichText text = tester.widget(find.byType(RichText).last);
-    expect(text.text.style!.color, iconThemeColor);
+    expect(text.text.style!.color, theme.colorScheme.secondary);
   });
 
-  testWidgets('Custom Icon Color - Theme - lowest preference for M3', (WidgetTester tester) async {
-    final ThemeData theme = ThemeData(useMaterial3: true);
+  testWidgets('Material2 - Custom Icon Color - Theme - lowest preference', (WidgetTester tester) async {
+    const Color iconThemeColor = Colors.yellow;
+    final ThemeData theme = ThemeData(useMaterial3: false, iconTheme: const IconThemeData(color: iconThemeColor));
     const AlertDialog dialog = AlertDialog(
       icon: Icon(Icons.ac_unit),
       actions: <Widget>[ ],
@@ -276,7 +322,7 @@ void main() {
 
     // first is Text('X')
     final RichText text = tester.widget(find.byType(RichText).last);
-    expect(text.text.style!.color, theme.colorScheme.secondary);
+    expect(text.text.style!.color, iconThemeColor);
   });
 
   testWidgets('Custom Title Text Style - Constructor Param', (WidgetTester tester) async {
@@ -313,13 +359,24 @@ void main() {
     expect(title.text.style, titleTextStyle);
   });
 
-  testWidgets('Custom Title Text Style - Theme', (WidgetTester tester) async {
+  testWidgets('Material3 - Custom Title Text Style - Theme', (WidgetTester tester) async {
     const String titleText = 'Title';
     const TextStyle titleTextStyle = TextStyle(color: Colors.pink);
-    const AlertDialog dialog = AlertDialog(
-      title: Text(titleText),
-      actions: <Widget>[ ],
-    );
+    const AlertDialog dialog = AlertDialog(title: Text(titleText));
+    final ThemeData theme = ThemeData(useMaterial3: true, textTheme: const TextTheme(headlineSmall: titleTextStyle));
+
+    await tester.pumpWidget(_appWithDialog(tester, dialog, theme: theme));
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    final RenderParagraph title = _getTextRenderObject(tester, titleText);
+    expect(title.text.style!.color, titleTextStyle.color);
+  });
+
+  testWidgets('Material2 - Custom Title Text Style - Theme', (WidgetTester tester) async {
+    const String titleText = 'Title';
+    const TextStyle titleTextStyle = TextStyle(color: Colors.pink);
+    const AlertDialog dialog = AlertDialog(title: Text(titleText));
     final ThemeData theme = ThemeData(useMaterial3: false, textTheme: const TextTheme(titleLarge: titleTextStyle));
 
     await tester.pumpWidget(_appWithDialog(tester, dialog, theme: theme));
@@ -412,13 +469,24 @@ void main() {
     expect(content.text.style, contentTextStyle);
   });
 
-  testWidgets('Custom Content Text Style - Theme', (WidgetTester tester) async {
+  testWidgets('Material3 - Custom Content Text Style - Theme', (WidgetTester tester) async {
     const String contentText = 'Content';
     const TextStyle contentTextStyle = TextStyle(color: Colors.pink);
-    const AlertDialog dialog = AlertDialog(
-      content: Text(contentText),
-      actions: <Widget>[ ],
-    );
+    const AlertDialog dialog = AlertDialog(content: Text(contentText),);
+    final ThemeData theme = ThemeData(useMaterial3: true, textTheme: const TextTheme(bodyMedium: contentTextStyle));
+
+    await tester.pumpWidget(_appWithDialog(tester, dialog, theme: theme));
+    await tester.tap(find.text('X'));
+    await tester.pumpAndSettle();
+
+    final RenderParagraph content = _getTextRenderObject(tester, contentText);
+    expect(content.text.style!.color, contentTextStyle.color);
+  });
+
+  testWidgets('Material2 - Custom Content Text Style - Theme', (WidgetTester tester) async {
+    const String contentText = 'Content';
+    const TextStyle contentTextStyle = TextStyle(color: Colors.pink);
+    const AlertDialog dialog = AlertDialog(content: Text(contentText));
     final ThemeData theme = ThemeData(useMaterial3: false, textTheme: const TextTheme(titleMedium: contentTextStyle));
 
     await tester.pumpWidget(_appWithDialog(tester, dialog, theme: theme));