Check for potential null operand in Not expressions.

pkg/analyzer/test/generated/resolver_test.dart

 // Copyright (c) 2014, 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.
 
 library engine.resolver_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/context/context.dart' as newContext;
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 2744 matching lines @@
 }
 f(A a) {
   A b;
   a += b;
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.DEPRECATED_MEMBER_USE]);
     verify([source]);
   }
 
-  void test_deprecatedAnnotationUse_Deprecated() {
+  void test_deprecatedAnnotationUse_deprecated() {
     Source source = addSource(r'''
 class A {
-  @Deprecated('0.9')
+  @deprecated
   m() {}
   n() {m();}
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.DEPRECATED_MEMBER_USE]);
     verify([source]);
   }
 
-  void test_deprecatedAnnotationUse_deprecated() {
+  void test_deprecatedAnnotationUse_Deprecated() {
     Source source = addSource(r'''
 class A {
-  @deprecated
+  @Deprecated('0.9')
   m() {}
   n() {m();}
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.DEPRECATED_MEMBER_USE]);
     verify([source]);
   }
 
   void test_deprecatedAnnotationUse_export() {
     Source source = addSource("export 'deprecated_library.dart';");
@@ skipping 476 matching lines @@
     Source source = addSource(r'''
 m(x) {
   if (x.a || x.b || x?.c) {}
 }
 ''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.NULL_AWARE_IN_CONDITION]);
     verify([source]);
   }
 
+  void test_nullAwareInCondition_if_not() {
+    Source source = addSource(r'''
+m(x) {
+  if (!x?.a) {}
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertErrors(source, [HintCode.NULL_AWARE_IN_CONDITION]);
+    verify([source]);
+  }
+
   void test_nullAwareInCondition_if_parenthesized() {
     Source source = addSource(r'''
 m(x) {
   if ((x?.a)) {}
 }
 ''');
     computeLibrarySourceErrors(source);
     assertErrors(source, [HintCode.NULL_AWARE_IN_CONDITION]);
     verify([source]);
   }
@@ skipping 11731 matching lines @@
 
   void _resolveTestUnit(String code) {
     testCode = code;
     testSource = addSource(testCode);
     LibraryElement library = resolve2(testSource);
     assertNoErrors(testSource);
     verify([testSource]);
     testUnit = resolveCompilationUnit(testSource, library);
   }
 }