Paths where '..' is not right between separators are normalized.

pkg/analyzer/test/src/util/absolute_path_test.dart

 // Copyright (c) 2015, 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 analyzer.test.src.util.absolute_path_test;
 
 import 'package:analyzer/src/util/absolute_path.dart';
 import 'package:unittest/unittest.dart';
 
 import '../../reflective_tests.dart';
@@ skipping 33 matching lines @@
     expect(context.isValid(r'/'), isTrue);
     expect(context.isValid(r''), isFalse);
     expect(context.isValid(r'foo/bar'), isFalse);
   }
 
   void test_isValid_normalized() {
     expect(context.isValid(r'/foo/bar'), isTrue);
     expect(context.isValid(r'/foo/..bar'), isTrue);
     expect(context.isValid(r'/foo/.bar/baz'), isTrue);
     expect(context.isValid(r'/foo/...'), isTrue);
+    expect(context.isValid(r'/foo/bar..'), isTrue);
     expect(context.isValid(r'/foo/.../bar'), isTrue);
     expect(context.isValid(r'/foo/.bar/.'), isFalse);
     expect(context.isValid(r'/foo/bar/../baz'), isFalse);
     expect(context.isValid(r'/foo/bar/..'), isFalse);
     expect(context.isValid(r'/foo/./bar'), isFalse);
     expect(context.isValid(r'/.'), isFalse);
   }
 
   void test_isWithin() {
     expect(context.isWithin(r'/root/path', r'/root/path/a'), isTrue);
@@ skipping 42 matching lines @@
     expect(context.isValid(r'C:\'), isTrue);
     expect(context.isValid(r''), isFalse);
     expect(context.isValid(r'foo\bar'), isFalse);
   }
 
   void test_isValid_normalized() {
     expect(context.isValid(r'C:\foo\bar'), isTrue);
     expect(context.isValid(r'C:\foo\..bar'), isTrue);
     expect(context.isValid(r'C:\foo\.bar\baz'), isTrue);
     expect(context.isValid(r'C:\foo\...'), isTrue);
+    expect(context.isValid(r'C:\foo\bar..'), isTrue);
     expect(context.isValid(r'C:\foo\...\bar'), isTrue);
     expect(context.isValid(r'C:\foo\.bar\.'), isFalse);
     expect(context.isValid(r'C:\foo\bar\..\baz'), isFalse);
     expect(context.isValid(r'C:\foo\bar\..'), isFalse);
     expect(context.isValid(r'C:\foo\.\bar'), isFalse);
     expect(context.isValid(r'C:\.'), isFalse);
   }
 
   void test_isWithin() {
     expect(context.isWithin(r'C:\root\path', r'C:\root\path\a'), isTrue);
     expect(context.isWithin(r'C:\root\path', r'C:\root\other'), isFalse);
     expect(context.isWithin(r'C:\root\path', r'C:\root\path'), isFalse);
   }
 
   void test_split() {
     expect(context.split(r'C:\path\to\foo'), [r'C:', r'path', r'to', r'foo']);
     expect(context.split(r'C:\path'), [r'C:', r'path']);
   }
 
   void test_suffix() {
     expect(
         context.suffix(r'C:\root\path', r'C:\root\path\a\b.dart'), r'a\b.dart');
     expect(context.suffix(r'C:\root\path', r'C:\root\other.dart'), isNull);
   }
 }