Optimize 'isWithin'.

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 test.analyzer.src.util.absolute_path;
 
 import 'package:analyzer/src/util/absolute_path.dart';
 import 'package:unittest/unittest.dart';
 
 import '../../reflective_tests.dart';
@@ skipping 32 matching lines @@
     expect(context.isWithin(r'/root/path', r'/root/other'), isFalse);
     expect(context.isWithin(r'/root/path', r'/root/path'), isFalse);
   }
 
   void test_split() {
     expect(context.split(r'/path/to/foo'), [r'', r'path', r'to', r'foo']);
     expect(context.split(r'/path'), [r'', r'path']);
   }
 
   void test_suffix() {
-    expect(context.suffix(r'/root/path/a/b.dart', r'/root/path'), r'a/b.dart');
-    expect(context.suffix(r'/root/other.dart', r'/root/path'), isNull);
+    expect(context.suffix(r'/root/path', r'/root/path/a/b.dart'), r'a/b.dart');
+    expect(context.suffix(r'/root/path', r'/root/other.dart'), isNull);
   }
 }
 
 @reflectiveTest
 class AbsolutePathContextWindowsTest {
   AbsolutePathContext context = new AbsolutePathContext(r'\');
 
   void test_append() {
     expect(context.append(r'C:\path\to', r'foo.dart'), r'C:\path\to\foo.dart');
   }
@@ skipping 18 matching lines @@
     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\a\b.dart', r'C:\root\path'), r'a\b.dart');
-    expect(context.suffix(r'C:\root\other.dart', r'C:\root\path'), isNull);
+        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);
   }
 }