Merge 253d628 into 0a1342c

lib/tree.rb

@@ -140,7 +140,7 @@ def root
     #
     # @return [Boolean] +true+ if this is a root node.
     def is_root?
-      @parent == nil
+      @parent.nil?
     end
 
     # @!attribute [r] has_content?
@@ -360,7 +360,7 @@ def <<(child)
     def add(child, at_index = -1)
       raise ArgumentError, "Attempting to add a nil node" unless child # Only handles the immediate child scenario
       raise ArgumentError, "Attempting add node to itself" if self.equal?(child)
-      raise ArgumentError, "Attempting add root as a child" if self.equal?(root) unless self.is_root?
+      raise ArgumentError, "Attempting add root as a child" if child.equal?(root)
 
       # Lazy mans unique test, won't test if children of child are unique in this tree too.
       raise "Child #{child.name} already added!" if @children_hash.include?(child.name)
@@ -482,6 +482,7 @@ def remove!(child)
     # @return [Tree::TreeNode] The parent node.
     def parent=(parent)         # :nodoc:
       @parent = parent
+      @node_depth = nil
     end
 
     protected :parent=, :name=
@@ -516,7 +517,7 @@ def remove_all!
     #
     # @return +nil+.
     def set_as_root!              # :nodoc:
-      @parent = nil
+      self.parent = nil
     end
 
     protected :set_as_root!

lib/tree/utils/metrics_methods.rb

@@ -94,8 +94,7 @@ def node_height
       #
       # @return [Integer] Depth of this node.
       def node_depth
-        return 0 if is_root?
-        1 + parent.node_depth
+        @node_depth ||= is_root? ? 0 : (1 + parent.node_depth)
       end
 
       # @!attribute [r] level

test/test_tree.rb

@@ -1470,11 +1470,7 @@ def test_add_node_to_self_as_child
 
       # And now a scenario where the node addition is done down the hierarchy
       child =  Tree::TreeNode.new("child")
-      begin
-        root << child << root
-      rescue ArgumentError => e
-        fail("The ArgumentError should not have been raised.")
-      end
+      assert_raise(ArgumentError) { root << child << root }
     end
 
     # Test whether the tree_leaf method works correctly