Compare XML docs independently of attribute order

invoicing/test/render_ubl_test.rb

@@ -7,20 +7,32 @@ class RenderUBLTest < Test::Unit::TestCase
   def reference_output(filename)
     IO.readlines(File.join(File.dirname(__FILE__), 'ref-output', filename)).join
   end
-
+
+  # Compares two strings, each being a serialised XML document, while ignoring
+  # the order of attributes within elements.
+  # TODO: this could generate much nicer error messages on failure.
+  def assert_equivalent_xml(doc1, doc2)
+    doc1, doc2 = [doc1, doc2].map do |doc|
+      doc.gsub(/(<[^\s>]+\s+)([^>]+)(>)/) do |match|
+        $1.to_s + $2.to_s.split(/\s+/).sort.join(' ') + $3.to_s
+      end
+    end
+    assert_equal doc1, doc2
+  end
+
   def test_render_ubl_invoice
-    assert_equal reference_output('invoice1.xml'), MyInvoice.find(1).render_ubl
+    assert_equivalent_xml reference_output('invoice1.xml'), MyInvoice.find(1).render_ubl
   end
 
   def test_render_ubl_self_billed_invoice
-    assert_equal reference_output('invoice2.xml'), MyInvoice.find(2).render_ubl
+    assert_equivalent_xml reference_output('invoice2.xml'), MyInvoice.find(2).render_ubl
   end
 
   def test_render_ubl_credit_note
     #File.open(File.join(File.dirname(__FILE__), 'ref-output', 'debug3.xml'), 'w') do |f|
     #  f.syswrite(MyCreditNote.find(3).render_ubl)
     #end
-    assert_equal reference_output('creditnote3.xml'),  MyCreditNote.find(3).render_ubl
+    assert_equivalent_xml reference_output('creditnote3.xml'),  MyCreditNote.find(3).render_ubl
   end
 
   def test_cannot_render_unknown_ledger_item_subtype