Sound null safety for framework and flutter_test (#68642)

diff --git a/dev/bots/test.dart b/dev/bots/test.dart
index 9b6bb83..b21dec1 100644
--- a/dev/bots/test.dart
+++ b/dev/bots/test.dart
@@ -528,7 +528,8 @@
 
 Future<void> _runFrameworkTests() async {
   final bq.BigqueryApi bigqueryApi = await _getBigqueryApi();
-  final List<String> nullSafetyOptions = <String>['--null-assertions', '--no-sound-null-safety'];
+  final List<String> soundNullSafetyOptions     = <String>['--enable-experiment=non-nullable', '--null-assertions', '--sound-null-safety'];
+  final List<String> mixedModeNullSafetyOptions = <String>['--enable-experiment=non-nullable', '--null-assertions', '--no-sound-null-safety'];
   final List<String> trackWidgetCreationAlternatives = <String>['--track-widget-creation', '--no-track-widget-creation'];
 
   Future<void> runWidgets() async {
@@ -536,7 +537,7 @@
     for (final String trackWidgetCreationOption in trackWidgetCreationAlternatives) {
       await _runFlutterTest(
         path.join(flutterRoot, 'packages', 'flutter'),
-        options: <String>[trackWidgetCreationOption, ...nullSafetyOptions],
+        options: <String>[trackWidgetCreationOption, ...soundNullSafetyOptions],
         tableData: bigqueryApi?.tabledata,
         tests: <String>[ path.join('test', 'widgets') + path.separator ],
       );
@@ -562,7 +563,7 @@
     for (final String trackWidgetCreationOption in trackWidgetCreationAlternatives) {
       await _runFlutterTest(
         path.join(flutterRoot, 'packages', 'flutter'),
-        options: <String>[trackWidgetCreationOption, ...nullSafetyOptions],
+        options: <String>[trackWidgetCreationOption, ...soundNullSafetyOptions],
         tableData: bigqueryApi?.tabledata,
         tests: tests,
       );
@@ -613,14 +614,14 @@
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'manual_tests'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'tools', 'vitool'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'examples', 'hello_world'), tableData: bigqueryApi?.tabledata);
-    await _runFlutterTest(path.join(flutterRoot, 'examples', 'layers'), tableData: bigqueryApi?.tabledata);
+    await _runFlutterTest(path.join(flutterRoot, 'examples', 'layers'), tableData: bigqueryApi?.tabledata, options: mixedModeNullSafetyOptions);
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'benchmarks', 'test_apps', 'stocks'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_driver'), tableData: bigqueryApi?.tabledata, tests: <String>[path.join('test', 'src', 'real_tests')]);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_goldens'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_localizations'), tableData: bigqueryApi?.tabledata);
-    await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_test'), tableData: bigqueryApi?.tabledata, options: nullSafetyOptions);
+    await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_test'), tableData: bigqueryApi?.tabledata, options: soundNullSafetyOptions);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'fuchsia_remote_debug_protocol'), tableData: bigqueryApi?.tabledata);
-    await _runFlutterTest(path.join(flutterRoot, 'dev', 'integration_tests', 'non_nullable'), options: nullSafetyOptions);
+    await _runFlutterTest(path.join(flutterRoot, 'dev', 'integration_tests', 'non_nullable'), options: mixedModeNullSafetyOptions);
     await _runFlutterTest(
       path.join(flutterRoot, 'dev', 'tracing_tests'),
       options: <String>['--enable-vmservice'],