Add test requested in earlier CL

Change-Id: I112004e06150ed913d64b77f272a4ae85c6ef61a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/156926
Auto-Submit: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analysis_server/test/src/services/correction/fix/add_null_check_test.dart

diff --git a/pkg/analysis_server/test/src/services/correction/fix/add_null_check_test.dart b/pkg/analysis_server/test/src/services/correction/fix/add_null_check_test.dart
index 6589af2..67c35f1 100644
--- a/pkg/analysis_server/test/src/services/correction/fix/add_null_check_test.dart
+++ b/pkg/analysis_server/test/src/services/correction/fix/add_null_check_test.dart
@@ -61,7 +61,8 @@
 ''');
   }
 
-  Future<void> test_assignment_differByMoreThanNullability() async {
+  Future<void>
+      test_assignment_differByMoreThanNullability_nonNullableRight() async {
     await resolveTestUnit('''
 void f(int x, String y) {
   x = y;
@@ -70,6 +71,16 @@
     await assertNoFix();
   }
 
+  Future<void>
+      test_assignment_differByMoreThanNullability_nullableRight() async {
+    await resolveTestUnit('''
+void f(int x, String? y) {
+  x = y;
+}
+''');
+    await assertNoFix();
+  }
+
   Future<void> test_assignment_needsParens() async {
     await resolveTestUnit('''
 void f(A x) {