More user friendly error message.

src/saml2/assertion.py

@@ -93,10 +93,8 @@ def filter_on_attributes(ava, required=None, optional=None, acs=None):
     if required is None:
         required = []
 
+    nform = "friendly_name"
     for attr in required:
-        found = False
-        nform = ""
-        for nform in ["friendly_name", "name"]:
         try:
             _name = attr[nform]
         except KeyError:
@@ -107,18 +105,21 @@ def filter_on_attributes(ava, required=None, optional=None, acs=None):
                 continue
 
         _fn = _match(_name, ava)
+        if not _fn:  # In the unlikely case that someone has provided us
+                     # with URIs as attribute names
+            _fn = _match(attr["name"], ava)
+
         if _fn:
             try:
                 values = [av["text"] for av in attr["attribute_value"]]
             except KeyError:
                 values = []
             res[_fn] = _filter_values(ava[_fn], values, True)
-                found = True
-                break
-
-        if not found:
-            raise MissingValue("Required attribute missing: '%s'" % (
-                attr[nform],))
+            continue
+        else:
+            desc = "Required attribute missing: '%s' (%s)" % (attr["name"],
+                                                              _name)
+            raise MissingValue(desc)
 
     if optional is None:
         optional = []