       newRootView = RootView.deserialize(rootView.serialize())
       rootView.deactivate() # Deactivates previous TreeView
 
-      newRootView.activateExtension(TreeView)
+      newRootView.activatePackage(TreeView)
 
       newTreeView = newRootView.find(".tree-view").view()
 

    rootView = new RootView(require.resolve('fixtures/tree-view'))
    project = rootView.project

    rootView.activateExtension(TreeView)
    treeView = rootView.find(".tree-view").view()
    treeView.root = treeView.find('> li:first').view()
    sampleJs = treeView.find('.file:contains(tree-view.js)')


      rootView = new RootView(rootDirPath)
      project = rootView.project
      rootView.activatePackage(TreeView)
      treeView = rootView.find(".tree-view").view()
      dirView = treeView.root.entries.find('.directory:contains(test-dir)').view()
      dirView.expand()
