Test for the 'importing a package library' fix.

pkg/analyzer/lib/source/package_map_resolver.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 source.package_map_resolver;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 
@@ skipping 66 matching lines @@
           }
         }
       }
     }
     // Return a NonExistingSource instance.
     // This helps provide more meaningful error messages to users
     // (a missing file error, as opposed to an invalid URI error).
     return new NonExistingSource(uri.toString(), UriKind.PACKAGE_URI);
   }
 
+  @override
+  Uri restoreAbsolute(Source source) {
+    String sourcePath = source.fullName;
+    for (String pkgName in packageMap.keys) {
+      List<Folder> pkgFolders = packageMap[pkgName];
+      for (Folder pkgFolder in pkgFolders) {
+        String pkgFolderPath = pkgFolder.path;
+        if (sourcePath.startsWith(pkgFolderPath)) {
+          String relPath = sourcePath.substring(pkgFolderPath.length);
+          return new Uri(path: '${PACKAGE_SCHEME}:$pkgName$relPath');
+        }
+      }
+    }
+    return null;
+  }
+
   /**
    * Returns `true` if [uri] is a `package` URI.
    */
   static bool isPackageUri(Uri uri) {
     return uri.scheme == PACKAGE_SCHEME;
   }
 }