Condense arrange_nodes

calculating the depths is not necessary.
Just checking parent nodes works well enough

OrderedHash are no longer necessary

lib/ancestry/class_methods.rb

@@ -38,22 +38,16 @@ def arrange options = {}
 
     # Arrange array of nodes into a nested hash of the form
     # {node => children}, where children = {} if the node has no children
+    # If a node's parent is not included, the node will be included as if it is a top level node
     def arrange_nodes(nodes)
-      arranged = ActiveSupport::OrderedHash.new
-      nodes_ids = nodes.map(&:id)
-      min_depth = nodes.map(&:depth).min
-      index = Hash.new { |h, k| h[k] = ActiveSupport::OrderedHash.new }
+      node_ids = Set.new(nodes.map(&:id))
+      index = Hash.new { |h, k| h[k] = {} }
 
-      nodes.each do |node|
+      nodes.each_with_object({}) do |node, arranged|
         children = index[node.id]
         index[node.parent_id][node] = children
-
-        if node.depth == min_depth || !nodes_ids.include?(node.parent_id)
-          arranged[node] = children
-        end
+        arranged[node] = children unless node_ids.include?(node.parent_id)
       end
-
-      arranged
     end
 
      # Arrangement to nested array

test/concerns/arrangement_test.rb

@@ -202,8 +202,7 @@ def test_arrangement_nesting
     end
   end
 
-  # TODO: don't drop parentless nodes
-  def xtest_arrange_partial
+  def test_arrange_partial
     AncestryTestDatabase.with_model do |model|
       # - n1
       #   - n2

test/concerns/sort_by_ancestry_test.rb

@@ -41,8 +41,7 @@ def test_sort_by_ancestry_no_parents_siblings
     end
   end
 
-  # TODO: don't drop parentless nodes
-  def xtest_sort_by_ancestry_no_parents_same_level
+  def test_sort_by_ancestry_no_parents_same_level
     AncestryTestDatabase.with_model do |model|
       n1, n2, n3, n4, n5, n6 = build_tree(model)
 
@@ -58,8 +57,7 @@ def test_sort_by_ancestry_partial_tree
     end
   end
 
-  # TODO: don't drop parentless nodes
-  def xtest_sort_by_ancestry_missing_parent_middle_of_tree
+  def test_sort_by_ancestry_missing_parent_middle_of_tree
     AncestryTestDatabase.with_model do |model|
       n1, n2, n3, n4, n5, n6 = build_tree(model)
 
@@ -128,7 +126,6 @@ def test_sort_by_ancestry_with_block_no_parents_all_children
     end
   end
 
-  # TODO: don't drop parentless nodes
   # TODO: nodes need to follow original ordering
   # NOTE: even for partial trees, if the input records are ranked, the output works
   def xtest_sort_by_ancestry_with_sql_sort_paginated_missing_parents_and_children
@@ -139,7 +136,7 @@ def xtest_sort_by_ancestry_with_sql_sort_paginated_missing_parents_and_children
     end
   end
 
-  # TODO: don't drop parentless nodes
+  # TODO: find a way to rank missing nodes
   def xtest_sort_by_ancestry_with_block_paginated_missing_parents_and_children
     AncestryTestDatabase.with_model :extra_columns => {:rank => :integer} do |model|
       n1, n2, n3, n4, n5, n6 = build_ranked_tree(model)