add tests for preserving xml namespace

Author: jacalata

tableaudocumentapi/xfile.py

@@ -28,7 +28,8 @@ def xml_open(filename, expected_root=None):
     # Is the file a zip (.twbx or .tdsx)
     if zipfile.is_zipfile(filename):
         tree = get_xml_from_archive(filename)
-    else:
+    else:   
+        _register_all_namespaces()
         tree = ET.parse(filename)
 
     # Is the file a supported version
@@ -54,6 +55,9 @@ def temporary_directory(*args, **kwargs):
     finally:
         shutil.rmtree(d)
 
+def _register_all_namespaces():    
+    # TO DO: should look at the file to find namespaces, not hardcode this one
+    ET.register_namespace("user","http://www.tableausoftware.com/xml/user")
 
 def find_file_in_zip(zip_file):
     '''Returns the twb/tds file from a Tableau packaged file format. Packaged
@@ -120,7 +124,9 @@ def save_into_archive(xml_tree, filename, new_filename=None):
 
 
 def _save_file(container_file, xml_tree, new_filename=None):
-
+    
+    _register_all_namespaces() # this shouldn't be necessary, should be done on open
+ 
     if new_filename is None:
         new_filename = container_file