anchor.diff:  // Copyright (c) 2019, 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.
  -
  -// @dart = 2.9
   
   /// This executable provides the ability to run the migration tool in process
   /// on a single package.  It should be invoked with two command-line arguments:
  
positive.code:     } else if (builtInPackages.contains(packageName)) {
        return path.join(sdkRoot, 'pkg', packageName);
      } else if (externalPackages.containsKey(packageName)) {
        return externalPackages[packageName];
      } else {
        throw StateError('Unrecognized package $packageName');
      }
  
negative.code: 
    void tearDown() {
      server.done();
    }
  
    /// Returns a [Future] that completes when the server's analysis is complete.
  