[analyzer] Add trailing comma test for null-aware elements

Part of #56989

Change-Id: Iad92a1144374ba24cc5b228f7e4b58c6329c8fbd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/405380
Commit-Queue: Chloe Stefantsova <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: chloestefantsova

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

@@ -184,6 +184,27 @@ void f() {
 ''');
   }
 
+  Future<void> test_list_literal_withNullAwareElement() async {
+    await resolveTestCode('''
+void f(String? s) {
+  var l = [
+    'a',
+    ?s
+  ];
+  print(l);
+}
+''');
+    await assertHasFix('''
+void f(String? s) {
+  var l = [
+    'a',
+    ?s,
+  ];
+  print(l);
+}
+''');
+  }
+
   Future<void> test_map_literal() async {
     await resolveTestCode('''
 void f() {
@@ -205,6 +226,48 @@ void f() {
 ''');
   }
 
+  Future<void> test_map_literal_withNullAwareKey() async {
+    await resolveTestCode('''
+void f(String? k) {
+  var l = {
+    'a': 1,
+    ?k: 2
+  };
+  print(l);
+}
+''');
+    await assertHasFix('''
+void f(String? k) {
+  var l = {
+    'a': 1,
+    ?k: 2,
+  };
+  print(l);
+}
+''');
+  }
+
+  Future<void> test_map_literal_withNullAwareValue() async {
+    await resolveTestCode('''
+void f(int? v) {
+  var l = {
+    'a': 1,
+    'b': ?v
+  };
+  print(l);
+}
+''');
+    await assertHasFix('''
+void f(int? v) {
+  var l = {
+    'a': 1,
+    'b': ?v,
+  };
+  print(l);
+}
+''');
+  }
+
   Future<void> test_named() async {
     await resolveTestCode('''
 void f({a, b}) {
@@ -264,6 +327,27 @@ void f() {
   };
   print(l);
 }
+''');
+  }
+
+  Future<void> test_set_literal_withNullAwareElement() async {
+    await resolveTestCode('''
+void f(String? s) {
+  var l = {
+    'a',
+    ?s
+  };
+  print(l);
+}
+''');
+    await assertHasFix('''
+void f(String? s) {
+  var l = {
+    'a',
+    ?s,
+  };
+  print(l);
+}
 ''');
   }
 }