Return an Enumerator from each* methods when no block is given

lib/oga/xml/attribute.rb

@@ -99,12 +99,14 @@ module Oga
       end
 
       # @see [Oga::XML::Node#each_ancestor]
-      def each_ancestor(&block)
+      def each_ancestor
+        return to_enum(:each_ancestor) unless block_given?
+
         return unless element
 
         yield element
 
-        element.each_ancestor(&block)
+        element.each_ancestor { |ancestor| yield ancestor }
       end
 
       private

lib/oga/xml/node.rb

@@ -180,6 +180,8 @@ module Oga
       #
       # @yieldparam [Oga::XML::Node]
       def each_ancestor
+        return to_enum(:each_ancestor) unless block_given?
+
         node = parent
 
         while node.is_a?(XML::Element)

lib/oga/xml/node_set.rb

@@ -53,6 +53,8 @@ module Oga
       #
       # @yieldparam [Oga::XML::Node]
       def each
+        return to_enum(:each) unless block_given?
+
         @nodes.each { |node| yield node }
       end
 

lib/oga/xml/traversal.rb

@@ -27,6 +27,8 @@ module Oga
       #
       # @yieldparam [Oga::XML::Node] The current node.
       def each_node
+        return to_enum(:each_node) unless block_given?
+
         visit = children.to_a.reverse
 
         until visit.empty?