Fix buglet in xhtmldiff

Fixes one of two formely broken unit tests.

test/unit/diff_test.rb

@@ -86,6 +86,19 @@ class DiffTest < Test::Unit::TestCase
     assert_equal "<ins class='diffins'><div>foo</div></ins>", diff(a, b)
   end
   
+  def test_diff_for_tag_change
+    a = "<a>x</a>"
+    b = "<b>x</b>"
+    assert_equal "<del class='diffmod'><a>x</a></del><ins class='diffmod'><b>x</b></ins>", diff(a, b)
+  end
+
+  def test_diff_for_tag_change_II
+    a = "<ul>\n<li>x</li>\n<li>y</li>\n</ul>"
+    b = "<ol>\n<li>x</li>\n<li>y</li>\n</ol>"
+    assert_equal "<del class='diffmod'><ul>\n<li>x</li>\n<li>y</li>\n</ul>" +
+          "</del><ins class='diffmod'><ol>\n<li>x</li>\n<li>y</li>\n</ol></ins>", diff(a, b)
+  end
+
   # FIXME this test fails (ticket #67, http://dev.instiki.org/ticket/67)
   def test_html_diff_preserves_endlines_in_pre
     a = "<pre>a\nb\nc\n</pre>"
@@ -94,12 +107,5 @@ class DiffTest < Test::Unit::TestCase
         "<pre><span> a\n<del class='diffdel'>b\nc\n</del></span></pre>",
         diff(a, b))
   end
-  
-  # FIXME. xhtmldiff fails to detect any change here
-  def test_diff_for_tag_change
-    a = "<a>x</a>"
-    b = "<b>x</b>"
-    assert_equal "<del class='diffdel'><a>x</a></del><ins class='diffins'><b>x</b></ins>", diff(a, b)
-  end
 
 end

vendor/plugins/xhtmldiff/lib/xhtmldiff.rb

@@ -7,6 +7,7 @@
 # Tweaks by Jacques Distler <distler@golem.ph.utexas.edu>
 #  -- add classnames to <del> and <ins> elements added by XHTMLDiff,
 #     for better CSS styling
+#  -- detect change in element name, without change in content
 
 require 'diff/lcs'
 require 'rexml/document'
@@ -64,7 +65,7 @@ class XHTMLDiff
 			if a == b
 				return a.deep_clone
 			end
-			if REXML::HashableElementDelegator === a and REXML::HashableElementDelegator === b
+			if REXML::HashableElementDelegator === a and REXML::HashableElementDelegator === b and a.name == b.name
 				o = REXML::Element.new(a.name)
 				o.add_attributes  a.attributes
 				hd = self.new(o)