tests: fix generated_document tests with py 3.8 (#42359)

tests/test_form_pages.py

@@ -12,6 +12,7 @@ import zipfile
 import base64
 from webtest import Upload, Hidden
 import mock
+import xml.etree.ElementTree as ET
 
 try:
     from PIL import Image
@@ -64,7 +65,15 @@ def assert_equal_zip(stream1, stream2):
     for name in z1.namelist():
         if name == 'styles.xml':
             continue
-        t1, t2 = z1.read(name), z2.read(name)
+        if name in ['content.xml', 'meta.xml']:
+            t1, t2 = ET.tostring(ET.XML(z1.read(name))), ET.tostring(ET.XML(z2.read(name)))
+            try:
+                # >= python 3.8: tostring preserves attribute order; use canonicalize to sort them
+                t1, t2 = ET.canonicalize(t1), ET.canonicalize(t2)
+            except AttributeError:
+                pass
+        else:
+            t1, t2 = z1.read(name), z2.read(name)
         assert t1 == t2, 'file "%s" differs' % name