WIP python3: fix xmlunwrap and its test to align with the use of bytes

FIXME: I'm quite unsure why xcp.xmlunwrap would want to use bytes and not
unicode strings, but the encode/decode calls make it quite clear it wants
to work with bytes.  That makes the API painful to use in python3.

Author: ydirson

tests/test_xmlunwrap.py

@@ -18,18 +18,18 @@ def test(self):
 
         self.assertEqual([getText(el)
                           for el in getElementsByTagName(self.top_el, ["fred"])],
-                         ["text1", "text2"])
+                         [b"text1", b"text2"])
 
-        x = getMapAttribute(self.top_el, ["mode"], [('test', 42), ('stuff', 77)])
+        x = getMapAttribute(self.top_el, ["mode"], [(b'test', 42), (b'stuff', 77)])
         self.assertEqual(x, 42)
-        x = getMapAttribute(self.top_el, ["made"], [('test', 42), ('stuff', 77)],
-                            default='stuff')
+        x = getMapAttribute(self.top_el, ["made"], [(b'test', 42), (b'stuff', 77)],
+                            default=b'stuff')
         self.assertEqual(x, 77)
 
         x = getStrAttribute(self.top_el, ["mode"])
-        self.assertEqual(x, "test")
+        self.assertEqual(x, b"test")
         x = getStrAttribute(self.top_el, ["made"])
-        self.assertEqual(x, "")
+        self.assertEqual(x, b"")
         x = getStrAttribute(self.top_el, ["made"], None)
         self.assertEqual(x, None)
 

xcp/xmlunwrap.py

@@ -44,11 +44,11 @@ def getElementsByTagName(el, tags, mandatory = False):
         raise XmlUnwrapError("Missing mandatory element %s" % tags[0])
     return matching
 
-def getStrAttribute(el, attrs, default = '', mandatory = False):
+def getStrAttribute(el, attrs, default=b'', mandatory=False):
     matching = []
     for attr in attrs:
         val = el.getAttribute(attr).encode()
-        if val != '':
+        if val != b'':
             matching.append(val)
     if len(matching) == 0:
         if mandatory: