#389. More NNBD static errors tests added
diff --git a/LanguageFeatures/nnbd/static_errors_A20_t01.dart b/LanguageFeatures/nnbd/static_errors_A20_t01.dart
new file mode 100644
index 0000000..bf9f6d3
--- /dev/null
+++ b/LanguageFeatures/nnbd/static_errors_A20_t01.dart
@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
+ * for details. All rights reserved. Use of this source code is governed by a
+ * BSD-style license that can be found in the LICENSE file.
+ */
+/**
+ * @assertion It is a warning to use a null aware operator (?., ?.., ??, ??=,
+ * or ...?) on a non-nullable receiver.
+ *
+ * @description Check it is a warning to use a null aware operator (?., ?.., ??,
+ * ??=, or ...?) on a non-nullable receiver.
+ * @author sgrekhov@unipro.ru
+ */
+// SharedOptions=--enable-experiment=non-nullable
+class A {
+ test() {}
+}
+
+class C extends A {
+
+}
+
+main() {
+ A a = A();
+ C c = C();
+ c?.test(); //# 01: static-type warning
+ c?..test(); //# 02: static-type warning
+ c ?? a; //# 03: static-type warning
+ a ??= c; //# 04: static-type warning
+ List<C> clist = [C(), C()];
+ List<A> alist = [A(), C(), ...? clist]; //# 05: static-type warning
+}
