anchor.diff:    /**
      * Compute the paths to be returned by the enclosing method given that the
      * plugin should exist in the given [pluginFolder].
  +   *
  +   * Runs pub if [pubCommand] is provided and not null.
      */
     List<String> _computePaths(Folder pluginFolder,
  -      {bool runPub: false, Workspace workspace}) {
  +      {String pubCommand, Workspace workspace}) {
       File pluginFile = pluginFolder
           .getChildAssumingFolder('bin')
           .getChildAssumingFile('plugin.dart');
  
positive.code:     if (parentFolder.exists) {
        Folder executionFolder =
            parentFolder.getChildAssumingFolder(pluginFolder.shortName);
        return _computePaths(executionFolder);
      }
      Folder executionFolder = pluginFolder.copyTo(parentFolder);
      return _computePaths(executionFolder, runPub: true);
    }
  
    /**
  
negative.code:         reason ??= 'File "${packagesFile.path}" does not exist.';
          packagesFile = null;
        }
      } else if (!packagesFile.exists) {
        if (workspace != null) {
          packagesFile =
              _createPackagesFile(pluginFolder, workspace.packageUriResolver);
  