Added parent-child relationship to pages to visualize a breadcrump and subpages.

app/controllers/pages_controller.rb

@@ -24,6 +24,7 @@ class PagesController < ApplicationController
   def new
     @page = Page.new
     @page.title = params[:title].gsub("_", " ") if params[:title]
+    @page.parent = Page.find_by_permalink(params[:parent]) if params[:parent]
 
     respond_to do |format|
       format.html # new.html.erb

app/helpers/application_helper.rb

@@ -95,8 +95,13 @@ module ApplicationHelper
   end
   
   # to set a title for both the h1-tag and the title in the header
-  def title(page_title)
+  def title(page_title, show_title = true)
-    content_for(:title) { page_title }
+    @content_for_title = page_title.to_s
+    @show_title = show_title
+  end
+
+  def show_title?
+    @show_title
   end
 
   def tab_is_active?(tab)

app/helpers/pages_helper.rb

@@ -9,10 +9,13 @@ module PagesHelper
 #    end
 #  end
 
-  def wikified_body(body)
+  def wikified_body(page)
-    WikiCloth.new({:data => body, :link_handler => Wikilink.new}).to_html
+    WikiCloth.new({:data => page.body, :link_handler => Wikilink.new, :params => {:referer => page.title}}).to_html
   end
 
+  def link_to_wikipage(page)
+    link_to page.title, "/wiki/#{page.title}"
+  end
 #  def generate_toc(body)
 #    toc = ""
 #    body.gsub(/^([=]{1,6})\s*(.*?)\s*(\1)/) do

app/models/page.rb

@@ -19,6 +19,7 @@ class Page < ActiveRecord::Base
 
   acts_as_versioned :version_column => :lock_version
   self.non_versioned_columns += ['permalink', 'created_at', 'title']
+  acts_as_tree :order => "title"
 
   attr_accessor :old_title # Save title to create redirect page when editing title
 

app/views/layouts/application.haml

@@ -27,7 +27,7 @@
         - if flash[:error]
           %h3.error#flashError= flash[:error]
         #loader{:style => "display:none;"}= image_tag("loader.gif", :border => 0)
-        - if yield(:title)
+        - if show_title?
           %h1= yield(:title)
         = yield
 

app/views/pages/_body.html.haml

@@ -1,4 +1,4 @@
-- content = wikified_body @page.body
+- content = wikified_body @page
 //#toc
 //%h2 Inhaltsverzeichnis
 //= generate_toc @page.body

app/views/pages/_form.html.haml

@@ -21,8 +21,9 @@
 - form_for @page do |f|
   = f.error_messages
   = f.hidden_field :lock_version
+  = f.hidden_field :parent_id
   %p
-    %b Title
+    %b Titel
     %br/
     = f.text_field :title
   %p

app/views/pages/show.html.haml

@@ -1,6 +1,14 @@
-- title @page.title
+- title @page.title, false
 
-#page-versions{:style => "float:right;margin-top:-2%;text-align:right;"}
+%h1
+  %span#breadcrump
+    - for page in @page.ancestors.reverse
+      = link_to_wikipage(page)
+      >>
+  = @page.title
+
+#sidebar
+  #page-versions
     = link_to "Bearbeiten", edit_page_path(@page)
     = link_to_function "Versionen (#{@page.versions.count})", "Element.toggle('versions')"
     #versions{:style => "display:none"}
@@ -10,6 +18,13 @@
             = link_to I18n.l(version.updated_at, :format => "%d.%m.%y %H:%M"), version_page_path(@page, :version => version.lock_version)
             = "(#{User.find(version.updated_by).nick})"
 
+  - unless @page.children.empty?
+    #children
+      %h2 Unterseiten
+      %ul
+        - for page in @page.children
+          %li= link_to_wikipage(page)
+
 = render :partial => 'body'
 
 %hr.clear/

db/migrate/20090325175756_create_pages.rb

@@ -7,6 +7,7 @@ class CreatePages < ActiveRecord::Migration
       t.integer :lock_version, :default => 0
       t.integer :updated_by
       t.integer :redirect
+      t.integer :parent_id
 
       t.timestamps
     end

db/schema.rb

@@ -9,7 +9,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20090317175355) do
+ActiveRecord::Schema.define(:version => 20090812110010) do
 
   create_table "article_categories", :force => true do |t|
     t.string "name",        :default => "", :null => false
@@ -37,16 +37,16 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.string   "manufacturer"
     t.string   "origin"
     t.datetime "shared_updated_on"
-    t.decimal  "price"
+    t.decimal  "price",               :precision => 8, :scale => 2
     t.float    "tax"
-    t.decimal  "deposit",             :default => 0.0
+    t.decimal  "deposit",             :precision => 8, :scale => 2, :default => 0.0
     t.integer  "unit_quantity",                                     :default => 1,    :null => false
     t.string   "order_number"
     t.datetime "created_at"
     t.datetime "updated_at"
-    t.integer  "quantity",            :default => 0
     t.datetime "deleted_at"
     t.string   "type"
+    t.integer  "quantity",                                          :default => 0
   end
 
   add_index "articles", ["name", "supplier_id"], :name => "index_articles_on_name_and_supplier_id"
@@ -75,6 +75,7 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.integer  "supplier_id"
     t.date     "delivered_on"
     t.datetime "created_at"
+    t.text     "note"
   end
 
   create_table "financial_transactions", :force => true do |t|
@@ -98,7 +99,7 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.integer  "quantity",                                       :default => 0, :null => false
     t.integer  "tolerance",                                      :default => 0, :null => false
     t.datetime "updated_on",                                                    :null => false
-    t.integer  "result"
+    t.decimal  "result",           :precision => 8, :scale => 3
   end
 
   add_index "group_order_articles", ["group_order_id", "order_article_id"], :name => "goa_index", :unique => true
@@ -118,7 +119,7 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.string   "type",                                              :default => "",    :null => false
     t.string   "name",                                              :default => "",    :null => false
     t.string   "description"
-    t.decimal  "account_balance",     :default => 0.0,   :null => false
+    t.decimal  "account_balance",     :precision => 8, :scale => 2, :default => 0.0,   :null => false
     t.datetime "account_updated"
     t.datetime "created_on",                                                           :null => false
     t.boolean  "role_admin",                                        :default => false, :null => false
@@ -135,6 +136,7 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.string   "contact_person"
     t.string   "contact_phone"
     t.string   "contact_address"
+    t.text     "stats"
   end
 
   add_index "groups", ["name"], :name => "index_groups_on_name", :unique => true
@@ -152,16 +154,16 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
   create_table "invoices", :force => true do |t|
     t.integer  "supplier_id"
     t.integer  "delivery_id"
+    t.integer  "order_id"
     t.string   "number"
     t.date     "date"
     t.date     "paid_on"
     t.text     "note"
     t.decimal  "amount",         :precision => 8, :scale => 2, :default => 0.0, :null => false
-    t.datetime "created_at"
-    t.datetime "updated_at"
-    t.integer  "order_id"
     t.decimal  "deposit",        :precision => 8, :scale => 2, :default => 0.0, :null => false
     t.decimal  "deposit_credit", :precision => 8, :scale => 2, :default => 0.0, :null => false
+    t.datetime "created_at"
+    t.datetime "updated_at"
   end
 
   create_table "memberships", :force => true do |t|
@@ -211,6 +213,34 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.decimal  "foodcoop_result",    :precision => 8, :scale => 2
   end
 
+  create_table "page_versions", :force => true do |t|
+    t.integer  "page_id"
+    t.integer  "lock_version"
+    t.text     "body"
+    t.integer  "updated_by"
+    t.integer  "redirect"
+    t.integer  "parent_id"
+    t.datetime "updated_at"
+  end
+
+  add_index "page_versions", ["page_id"], :name => "index_page_versions_on_page_id"
+
+  create_table "pages", :force => true do |t|
+    t.string   "title"
+    t.text     "body"
+    t.string   "permalink"
+    t.integer  "lock_version", :default => 0
+    t.integer  "updated_by"
+    t.integer  "redirect"
+    t.integer  "parent_id"
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
+  create_table "schema_info", :id => false, :force => true do |t|
+    t.integer "version"
+  end
+
   create_table "stock_changes", :force => true do |t|
     t.integer  "delivery_id"
     t.integer  "order_id"
@@ -256,6 +286,7 @@ ActiveRecord::Schema.define(:version => 20090317175355) do
     t.datetime "created_on",                        :null => false
     t.datetime "updated_on",                        :null => false
     t.integer  "required_users", :default => 1
+    t.boolean  "weekly"
   end
 
   add_index "tasks", ["due_date"], :name => "index_tasks_on_due_date"

lib/wikilink.rb

@@ -1,15 +1,19 @@
 class Wikilink < WikiCloth::WikiLinkHandler
 
-  def url_for(page)
+  def url_for(page, parent = nil)
+    if parent
+      "/pages/new?title=#{page}&parent=#{parent}"
+    else
       "/wiki/#{page}"
     end
+  end
 
   def link_attributes_for(page)
     permalink = Page.permalink(page)
     if Page.exists?(:permalink => permalink)
      { :href => url_for(permalink) }
     else
-     { :href => url_for(page), :class =>  "new_wiki_link"}
+     { :href => url_for(page, params[:referer]), :class =>  "new_wiki_link"}
     end
   end
 

public/stylesheets/main.css

@@ -448,6 +448,18 @@ a.new_wiki_link {
 #toc {
   float: right; }
 
+#breadcrump {
+  font-size: 0.5em; }
+  #breadcrump a {
+    color: #ed0606; }
+
+#sidebar {
+  float: right;
+  margin-top: -2%;
+  width: 20%; }
+  #sidebar #page-versions {
+    text-align: right; }
+
 #wiki_content h1, #wiki_content h2, #wiki_content h3, #wiki_content h4, #wiki_content h5 {
   color: black; }
 #wiki_content span.editsection {

public/stylesheets/print.css

@@ -448,6 +448,18 @@ a.new_wiki_link {
 #toc {
   float: right; }
 
+#breadcrump {
+  font-size: 0.5em; }
+  #breadcrump a {
+    color: #ed0606; }
+
+#sidebar {
+  float: right;
+  margin-top: -2%;
+  width: 20%; }
+  #sidebar #page-versions {
+    text-align: right; }
+
 #wiki_content h1, #wiki_content h2, #wiki_content h3, #wiki_content h4, #wiki_content h5 {
   color: black; }
 #wiki_content span.editsection {

public/stylesheets/sass/main.sass

@@ -493,6 +493,18 @@ a.new_wiki_link
   padding: 0 1em
 #toc
   float: right
+#breadcrump
+  font-size: 0.5em
+  a
+    :color = !main_red
+#sidebar
+  float: right
+  margin-top: -2%
+  width: 20%
+  #page-versions
+    text-align: right
+
+
 #wiki_content
   h1, h2, h3, h4, h5
     color: black

vendor/plugins/acts_as_tree/README

@@ -0,0 +1,26 @@
+acts_as_tree
+============
+
+Specify this +acts_as+ extension if you want to model a tree structure by providing a parent association and a children
+association. This requires that you have a foreign key column, which by default is called +parent_id+.
+
+  class Category < ActiveRecord::Base
+    acts_as_tree :order => "name"
+  end
+
+  Example:
+  root
+   \_ child1
+        \_ subchild1
+        \_ subchild2
+
+  root      = Category.create("name" => "root")
+  child1    = root.children.create("name" => "child1")
+  subchild1 = child1.children.create("name" => "subchild1")
+
+  root.parent   # => nil
+  child1.parent # => root
+  root.children # => [child1]
+  root.children.first.children.first # => subchild1
+
+Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license  

vendor/plugins/acts_as_tree/Rakefile

@@ -0,0 +1,22 @@
+require 'rake'
+require 'rake/testtask'
+require 'rake/rdoctask'
+
+desc 'Default: run unit tests.'
+task :default => :test
+
+desc 'Test acts_as_tree plugin.'
+Rake::TestTask.new(:test) do |t|
+  t.libs << 'lib'
+  t.pattern = 'test/**/*_test.rb'
+  t.verbose = true
+end
+
+desc 'Generate documentation for acts_as_tree plugin.'
+Rake::RDocTask.new(:rdoc) do |rdoc|
+  rdoc.rdoc_dir = 'rdoc'
+  rdoc.title    = 'acts_as_tree'
+  rdoc.options << '--line-numbers' << '--inline-source'
+  rdoc.rdoc_files.include('README')
+  rdoc.rdoc_files.include('lib/**/*.rb')
+end

vendor/plugins/acts_as_tree/init.rb

@@ -0,0 +1 @@
+ActiveRecord::Base.send :include, ActiveRecord::Acts::Tree

vendor/plugins/acts_as_tree/lib/active_record/acts/tree.rb

@@ -0,0 +1,96 @@
+module ActiveRecord
+  module Acts
+    module Tree
+      def self.included(base)
+        base.extend(ClassMethods)
+      end
+
+      # Specify this +acts_as+ extension if you want to model a tree structure by providing a parent association and a children
+      # association. This requires that you have a foreign key column, which by default is called +parent_id+.
+      #
+      #   class Category < ActiveRecord::Base
+      #     acts_as_tree :order => "name"
+      #   end
+      #
+      #   Example:
+      #   root
+      #    \_ child1
+      #         \_ subchild1
+      #         \_ subchild2
+      #
+      #   root      = Category.create("name" => "root")
+      #   child1    = root.children.create("name" => "child1")
+      #   subchild1 = child1.children.create("name" => "subchild1")
+      #
+      #   root.parent   # => nil
+      #   child1.parent # => root
+      #   root.children # => [child1]
+      #   root.children.first.children.first # => subchild1
+      #
+      # In addition to the parent and children associations, the following instance methods are added to the class
+      # after calling <tt>acts_as_tree</tt>:
+      # * <tt>siblings</tt> - Returns all the children of the parent, excluding the current node (<tt>[subchild2]</tt> when called on <tt>subchild1</tt>)
+      # * <tt>self_and_siblings</tt> - Returns all the children of the parent, including the current node (<tt>[subchild1, subchild2]</tt> when called on <tt>subchild1</tt>)
+      # * <tt>ancestors</tt> - Returns all the ancestors of the current node (<tt>[child1, root]</tt> when called on <tt>subchild2</tt>)
+      # * <tt>root</tt> - Returns the root of the current node (<tt>root</tt> when called on <tt>subchild2</tt>)
+      module ClassMethods
+        # Configuration options are:
+        #
+        # * <tt>foreign_key</tt> - specifies the column name to use for tracking of the tree (default: +parent_id+)
+        # * <tt>order</tt> - makes it possible to sort the children according to this SQL snippet.
+        # * <tt>counter_cache</tt> - keeps a count in a +children_count+ column if set to +true+ (default: +false+).
+        def acts_as_tree(options = {})
+          configuration = { :foreign_key => "parent_id", :order => nil, :counter_cache => nil }
+          configuration.update(options) if options.is_a?(Hash)
+
+          belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key], :counter_cache => configuration[:counter_cache]
+          has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => :destroy
+
+          class_eval <<-EOV
+            include ActiveRecord::Acts::Tree::InstanceMethods
+
+            def self.roots
+              find(:all, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}})
+            end
+
+            def self.root
+              find(:first, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}})
+            end
+          EOV
+        end
+      end
+
+      module InstanceMethods
+        # Returns list of ancestors, starting from parent until root.
+        #
+        #   subchild1.ancestors # => [child1, root]
+        def ancestors
+          node, nodes = self, []
+          nodes << node = node.parent while node.parent
+          nodes
+        end
+
+        # Returns the root node of the tree.
+        def root
+          node = self
+          node = node.parent while node.parent
+          node
+        end
+
+        # Returns all siblings of the current node.
+        #
+        #   subchild1.siblings # => [subchild2]
+        def siblings
+          self_and_siblings - [self]
+        end
+
+        # Returns all siblings and a reference to the current node.
+        #
+        #   subchild1.self_and_siblings # => [subchild1, subchild2]
+        def self_and_siblings
+          parent ? parent.children : self.class.roots
+        end
+      end
+    end
+  end
+end

vendor/plugins/acts_as_tree/test/acts_as_tree_test.rb

@@ -0,0 +1,219 @@
+require 'test/unit'
+
+require 'rubygems'
+require 'active_record'
+
+$:.unshift File.dirname(__FILE__) + '/../lib'
+require File.dirname(__FILE__) + '/../init'
+
+class Test::Unit::TestCase
+  def assert_queries(num = 1)
+    $query_count = 0
+    yield
+  ensure
+    assert_equal num, $query_count, "#{$query_count} instead of #{num} queries were executed."
+  end
+
+  def assert_no_queries(&block)
+    assert_queries(0, &block)
+  end
+end
+
+ActiveRecord::Base.establish_connection(:adapter => "sqlite3", :dbfile => ":memory:")
+
+# AR keeps printing annoying schema statements
+$stdout = StringIO.new
+
+def setup_db
+  ActiveRecord::Base.logger
+  ActiveRecord::Schema.define(:version => 1) do
+    create_table :mixins do |t|
+      t.column :type, :string
+      t.column :parent_id, :integer
+    end
+  end
+end
+
+def teardown_db
+  ActiveRecord::Base.connection.tables.each do |table|
+    ActiveRecord::Base.connection.drop_table(table)
+  end
+end
+
+class Mixin < ActiveRecord::Base
+end
+
+class TreeMixin < Mixin 
+  acts_as_tree :foreign_key => "parent_id", :order => "id"
+end
+
+class TreeMixinWithoutOrder < Mixin
+  acts_as_tree :foreign_key => "parent_id"
+end
+
+class RecursivelyCascadedTreeMixin < Mixin
+  acts_as_tree :foreign_key => "parent_id"
+  has_one :first_child, :class_name => 'RecursivelyCascadedTreeMixin', :foreign_key => :parent_id
+end
+
+class TreeTest < Test::Unit::TestCase
+  
+  def setup
+    setup_db
+    @root1 = TreeMixin.create!
+    @root_child1 = TreeMixin.create! :parent_id => @root1.id
+    @child1_child = TreeMixin.create! :parent_id => @root_child1.id
+    @root_child2 = TreeMixin.create! :parent_id => @root1.id
+    @root2 = TreeMixin.create!
+    @root3 = TreeMixin.create!
+  end
+
+  def teardown
+    teardown_db
+  end
+
+  def test_children
+    assert_equal @root1.children, [@root_child1, @root_child2]
+    assert_equal @root_child1.children, [@child1_child]
+    assert_equal @child1_child.children, []
+    assert_equal @root_child2.children, []
+  end
+
+  def test_parent
+    assert_equal @root_child1.parent, @root1
+    assert_equal @root_child1.parent, @root_child2.parent
+    assert_nil @root1.parent
+  end
+
+  def test_delete
+    assert_equal 6, TreeMixin.count
+    @root1.destroy
+    assert_equal 2, TreeMixin.count
+    @root2.destroy
+    @root3.destroy
+    assert_equal 0, TreeMixin.count
+  end
+
+  def test_insert
+    @extra = @root1.children.create
+
+    assert @extra
+
+    assert_equal @extra.parent, @root1
+
+    assert_equal 3, @root1.children.size
+    assert @root1.children.include?(@extra)
+    assert @root1.children.include?(@root_child1)
+    assert @root1.children.include?(@root_child2)
+  end
+
+  def test_ancestors
+    assert_equal [], @root1.ancestors
+    assert_equal [@root1], @root_child1.ancestors
+    assert_equal [@root_child1, @root1], @child1_child.ancestors
+    assert_equal [@root1], @root_child2.ancestors
+    assert_equal [], @root2.ancestors
+    assert_equal [], @root3.ancestors
+  end
+
+  def test_root
+    assert_equal @root1, TreeMixin.root
+    assert_equal @root1, @root1.root
+    assert_equal @root1, @root_child1.root
+    assert_equal @root1, @child1_child.root
+    assert_equal @root1, @root_child2.root
+    assert_equal @root2, @root2.root
+    assert_equal @root3, @root3.root
+  end
+
+  def test_roots
+    assert_equal [@root1, @root2, @root3], TreeMixin.roots
+  end
+
+  def test_siblings
+    assert_equal [@root2, @root3], @root1.siblings
+    assert_equal [@root_child2], @root_child1.siblings
+    assert_equal [], @child1_child.siblings
+    assert_equal [@root_child1], @root_child2.siblings
+    assert_equal [@root1, @root3], @root2.siblings
+    assert_equal [@root1, @root2], @root3.siblings
+  end
+
+  def test_self_and_siblings
+    assert_equal [@root1, @root2, @root3], @root1.self_and_siblings
+    assert_equal [@root_child1, @root_child2], @root_child1.self_and_siblings
+    assert_equal [@child1_child], @child1_child.self_and_siblings
+    assert_equal [@root_child1, @root_child2], @root_child2.self_and_siblings
+    assert_equal [@root1, @root2, @root3], @root2.self_and_siblings
+    assert_equal [@root1, @root2, @root3], @root3.self_and_siblings
+  end           
+end
+
+class TreeTestWithEagerLoading < Test::Unit::TestCase
+  
+  def setup 
+    teardown_db
+    setup_db
+    @root1 = TreeMixin.create!
+    @root_child1 = TreeMixin.create! :parent_id => @root1.id
+    @child1_child = TreeMixin.create! :parent_id => @root_child1.id
+    @root_child2 = TreeMixin.create! :parent_id => @root1.id
+    @root2 = TreeMixin.create!
+    @root3 = TreeMixin.create!
+    
+    @rc1 = RecursivelyCascadedTreeMixin.create!
+    @rc2 = RecursivelyCascadedTreeMixin.create! :parent_id => @rc1.id 
+    @rc3 = RecursivelyCascadedTreeMixin.create! :parent_id => @rc2.id
+    @rc4 = RecursivelyCascadedTreeMixin.create! :parent_id => @rc3.id
+  end
+
+  def teardown
+    teardown_db
+  end
+    
+  def test_eager_association_loading
+    roots = TreeMixin.find(:all, :include => :children, :conditions => "mixins.parent_id IS NULL", :order => "mixins.id")
+    assert_equal [@root1, @root2, @root3], roots                     
+    assert_no_queries do
+      assert_equal 2, roots[0].children.size
+      assert_equal 0, roots[1].children.size
+      assert_equal 0, roots[2].children.size
+    end   
+  end
+  
+  def test_eager_association_loading_with_recursive_cascading_three_levels_has_many
+    root_node = RecursivelyCascadedTreeMixin.find(:first, :include => { :children => { :children => :children } }, :order => 'mixins.id')
+    assert_equal @rc4, assert_no_queries { root_node.children.first.children.first.children.first }
+  end
+  
+  def test_eager_association_loading_with_recursive_cascading_three_levels_has_one
+    root_node = RecursivelyCascadedTreeMixin.find(:first, :include => { :first_child => { :first_child => :first_child } }, :order => 'mixins.id')
+    assert_equal @rc4, assert_no_queries { root_node.first_child.first_child.first_child }
+  end
+  
+  def test_eager_association_loading_with_recursive_cascading_three_levels_belongs_to
+    leaf_node = RecursivelyCascadedTreeMixin.find(:first, :include => { :parent => { :parent => :parent } }, :order => 'mixins.id DESC')
+    assert_equal @rc1, assert_no_queries { leaf_node.parent.parent.parent }
+  end 
+end
+
+class TreeTestWithoutOrder < Test::Unit::TestCase
+  
+  def setup                               
+    setup_db
+    @root1 = TreeMixinWithoutOrder.create!
+    @root2 = TreeMixinWithoutOrder.create!
+  end
+
+  def teardown
+    teardown_db
+  end
+
+  def test_root
+    assert [@root1, @root2].include?(TreeMixinWithoutOrder.root)
+  end
+  
+  def test_roots
+    assert_equal [], [@root1, @root2] - TreeMixinWithoutOrder.roots
+  end
+end