node.rb

require 'nokogiri'

module Nokogiri
  module XML
    class Node
      
      ##
      # Returns true of the argument is semantically equivalent to self
      # Equivalent is defined as follows :
      # - same name
      # - same attributes
      # - same same default namespace (different definitions are ok)
      # - same number of children
      # - each child is equivalent to one child of the argument
      # - the order of the children can be different
      def ===(_node)
        if _node.name != self.name
          false
        elsif _node.text != self.text
          false
        elsif (
          !_node.is_a?(Nokogiri::XML::Attr) and 
          !_node.is_a?(Nokogiri::XML::Attr) and (
            (!_node.namespace.nil? and self.namespace.nil?) or
            (_node.namespace.nil?  and !self.namespace.nil?) or
            (!_node.namespace.nil? and !self.namespace.nil? and _node.namespace.href != self.namespace.href)
          )
        )
          false
        elsif _node.attributes.count != self.attributes.count
          false
        elsif _node.children.count != self.children.count
          false
        else
          _node.attributes.each do |n, a|
            matched = false
            self.attributes.each do |m, b|
              if a === b
                matched = true
              end
            end
            return false unless matched
          end
          _node.children.each do |c|
            matched = false
            self.children.each do |d|
              if d === c
                matched = true
              end
            end
            return false unless matched
          end
          true
        end
      end
    end
  end
end

node_spec.rb

require 'rubygems'
require 'node'

describe :=== do
  before(:each) do
    @doc =  Nokogiri::XML::Document.new
  end

  describe "when comparing Attr" do
    before(:each) do
      @attr1 = Nokogiri::XML::Attr.new(@doc, "a")
      @attr1.value = "a"
    end

    context "when the other attributes has a different name" do
      before(:each) do
        @attr2 = Nokogiri::XML::Attr.new(@doc, "b")
      end
      it "should return false" do
        (@attr1 === @attr2).should be_false
      end
    end

    context "when the other attributes has the same name but a different value" do
      before(:each) do
        @attr2 = Nokogiri::XML::Attr.new(@doc, "a")
        @attr2.value = "b"
      end
      it "should return false" do
        (@attr1 === @attr2).should be_false
      end
    end

    context "when the other attributes has the same name and the same value" do
      before(:each) do
        @attr2 = Nokogiri::XML::Attr.new(@doc, "a")
        @attr2.value = @attr1.value
      end
      it "should return false" do
        (@attr1 === @attr2).should be_true
      end
    end

  end

  describe "when comparing Elements" do

    context "when 2 nodes have different names" do
      before(:each) do
        @node1 = Nokogiri::XML::Node.new("node1", @doc)
        @node2 = Nokogiri::XML::Node.new("node2", @doc)
      end

      it "should return false" do
        (@node1 === @node2).should be_false
      end
    end

    context "when 2 nodes have different set of attributes" do
      before(:each) do
        @node1 = Nokogiri::XML::Node.new("node1", @doc)
        @node2 = Nokogiri::XML::Node.new("node1", @doc)
      end

      it "should return false if the 2 nodes don't have the same number of attributes" do
        @node1["cool"] = "thegang"
        @node1["jackson"] = "five"
        @node2["jackson"] = "five"
        (@node1 === @node2).should be_false
      end

      it "should return true if the 2 nodes have the same attributes but in a different order" do
        @node1["cool"] = "thegang"
        @node1["jackson"] = "five"
        @node2["jackson"] = "five"
        @node2["cool"] = "thegang"
        (@node1 === @node2).should be_true
      end

      it "should return true if the 2 nodes have the same attributes but in the same order" do
        @node1["cool"] = "thegang"
        @node1["jackson"] = "five"
        @node2["cool"] = "thegang"
        @node2["jackson"] = "five"
        (@node1 === @node2).should be_true
      end

    end

    context "when 2 nodes have different default namespaces" do
      before(:each) do
        @node1 = Nokogiri::XML::Node.new("node1", @doc)
        @node2 = Nokogiri::XML::Node.new("node1", @doc)
      end

      it "should return false if the 2 nodes don't have the same namespace" do
        @node1.default_namespace= "http://mysupernamespace"
        (@node1 === @node2).should be_false
      end

      it "should return true if the 2 have the same namespace" do
        @node1.default_namespace= "http://mysupernamespace"
        @node2.default_namespace= "http://mysupernamespace"
        (@node1 === @node2).should be_true
      end

      it "should return true if the 2 have the same namespace, but then define different namespaces" do
        @node1.default_namespace= "http://mysupernamespace"
        @node1.add_namespace_definition("prefix", "http://anothernamespace")
        @node2.default_namespace= "http://mysupernamespace"
        (@node1 === @node2).should be_true
      end
    end

    context "when 2 nodes have a different number of children" do
      before(:each) do
        @node1 = Nokogiri::XML::Node.new("node1", @doc)
        @node1.add_child(Nokogiri::XML::Node.new("child1", @doc))
        @node1.add_child(Nokogiri::XML::Node.new("child1", @doc))
        @node2 = Nokogiri::XML::Node.new("node1", @doc)
        @node2.add_child(Nokogiri::XML::Node.new("child1", @doc))
      end
      it "should return false" do
        (@node1 === @node2).should be_false
      end
    end

    context "when 2 nodes have a different text" do
      before(:each) do
        @node1 = Nokogiri::XML::Node.new("node1", @doc)
        @node1.content= "hello world"
        @node2 = Nokogiri::XML::Node.new("node1", @doc)
        @node2.content= "Ciao"
      end
      it "should return false" do
        (@node1 === @node2).should be_false
      end
    end

    context "when 2 nodes have different children" do
      before(:each) do
        @node1 = Nokogiri::XML::Node.new("node1", @doc)
        @node1.add_child(Nokogiri::XML::Node.new("child1", @doc))
        @node1.add_child(Nokogiri::XML::Node.new("child2", @doc))
        @node2 = Nokogiri::XML::Node.new("node1", @doc)
        @node2.add_child(Nokogiri::XML::Node.new("child1", @doc))
        @node2.add_child(Nokogiri::XML::Node.new("child2different", @doc))
      end
      it "should return false" do
        (@node1 === @node2).should be_false
      end
    end

    context "when 2 documents are identical" do
      before(:each) do
        @doc1 = Nokogiri::XML::Builder.new do |xml|
          xml.root("age" => "23", "name" => "john Doe") {
            xml.products {
              xml.widget {
                xml.id_ "10"
                xml.name(:lang => "english") {
                 xml.text="Awesome widget" 
                }
              }
              xml.widget {
                xml.id_ "11"
                xml.name "Good widget"
              }
            }
          }
        end.doc
        
        xml= <<-EOXML
        <?xml version="1.0"?>
        <root name='john Doe' age="23" >
          <products>
            <widget>
              <id>11</id>
              <name lang="english">Good widget</name>
            </widget>
            <widget>
              <id>10</id>
              <name>Awesome widget</name>
            </widget>
          </products>
        </root>
        EOXML
        @doc2 = Nokogiri::XML(xml)
      end
      
      it "should return true" do
        (@node1 === @node2).should be_true
      end
    end
  end
end