Rework the whitespace/comment change detection.

pkg/analyzer/test/generated/incremental_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.incremental_resolver_test;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
+import 'package:analyzer/src/generated/incremental_logger.dart' as log;
 import 'package:analyzer/src/generated/incremental_resolver.dart';
-import 'package:analyzer/src/generated/incremental_logger.dart' as log;
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:analyzer/src/generated/testing/ast_factory.dart';
 import 'package:analyzer/src/generated/testing/element_factory.dart';
 import 'package:unittest/unittest.dart';
 
 import '../reflective_tests.dart';
@@ skipping 2323 matching lines @@
 }
 ''');
     _updateAndValidate(r'''
 /// aaa bbb
 main() {
   return 2;
 }
 ''');
   }
 
+  void test_endOfLineComment_add_beforeKeywordToken() {
+    _resolveUnit(r'''
+main() {
+  var v = 42;
+}
+''');
+    _updateAndValidate(r'''
+main() {
+  // some comment
+  var v = 42;
+}
+''');
+  }
+
+  void test_endOfLineComment_add_beforeStringToken() {
+    _resolveUnit(r'''
+main() {
+  print(0);
+}
+''');
+    _updateAndValidate(r'''
+main() {
+  // some comment
+  print(0);
+}
+''');
+  }
+
+  void test_endOfLineComment_edit() {
+    _resolveUnit(r'''
+main() {
+  // some comment
+  print(2);
+}
+''');
+    _updateAndValidate(r'''
+main() {
+  // edited comment text
+  print(0);
+}
+''');
+  }
+
+  void test_endOfLineComment_remove() {
+    _resolveUnit(r'''
+main() {
+  // some comment
+  print(0);
+}
+''');
+    _updateAndValidate(r'''
+main() {
+  print(0);
+}
+''');
+  }
+
   void test_false_topLevelFunction_name() {
     _resolveUnit(r'''
 a() {}
 b() {}
 ''');
     _updateAndValidate(r'''
 a() {}
 bb() {}
 ''', expectedSuccess: false);
   }
@@ skipping 463 matching lines @@
       _assertEqualToken(incrToken, fullToken);
       // comments
       {
         Token incrComment = incrToken.precedingComments;
         Token fullComment = fullToken.precedingComments;
         while (true) {
           if (fullComment == null) {
             expect(incrComment, isNull);
             break;
           }
+          expect(incrComment, isNotNull);
           _assertEqualToken(incrComment, fullComment);
           incrComment = incrComment.next;
           fullComment = fullComment.next;
         }
       }
       // next tokens
       incrToken = incrToken.next;
       fullToken = fullToken.next;
     }
   }
@@ skipping 1061 matching lines @@
     _visitList(node.metadata, other.metadata);
     _visitNode(node.identifier, other.identifier);
   }
 
   static void assertSameResolution(CompilationUnit actual,
       CompilationUnit expected) {
     _SameResolutionValidator validator = new _SameResolutionValidator(expected);
     actual.accept(validator);
   }
 }