better error message when incorrect data is passed to Selector "text" argument

Author: kmike

parsel/selector.py

@@ -189,7 +189,9 @@ def __init__(self, text=None, type=None, namespaces=None, root=None,
 
         if text is not None:
             if not isinstance(text, six.text_type):
-                raise TypeError("text argument should be of type %s" % six.text_type)
+                msg = "text argument should be of type %s, got %s" % (
+                           six.text_type, text.__class__)
+                raise TypeError(msg)
             root = self._get_root(text, base_url)
         elif root is None:
             raise ValueError("Selector needs either text or root argument")