Use a better __repr__ for User objects.

(NullUnrestrictedUser had a non-string repr that made it impossible to
debug properly.)

doc/CHANGES.txt

@@ -86,6 +86,8 @@ Zope Changes
 
     Other
 
+      - AccessControl.User: Use a better __repr__.
+
       - ZSQLMethod.manage_main: Moved the error message that warns of a
         non-existing or closed database connection next to the Connection ID
         dropdown and present it using red to increase its visibility.

lib/python/AccessControl/User.py

@@ -276,7 +276,8 @@ class BasicUser(Implicit):
 
     def __len__(self): return 1
     def __str__(self): return self.getUserName()
-    __repr__=__str__
+    def __repr__(self):
+        return '<%s %r>' % (self.__class__.__name__, self.getUserName())
 
 
 class SimpleUser(BasicUser):

lib/python/AccessControl/tests/testUserFolder.py

@@ -275,6 +275,21 @@ class UserTests(unittest.TestCase):
         f = User('chris', '123', ['Manager'], [])
         self.assertEqual(f.getDomains(), ())
 
+    def testRepr(self):
+        f = User('flo', '123', ['Manager'], [])
+        self.assertEqual(repr(f), "<User 'flo'>")
+
+    def testReprSpecial(self):
+        from AccessControl.User import NullUnrestrictedUser
+        from AccessControl.User import nobody
+        from AccessControl.User import system
+        # NullUnrestrictedUser is used when there is no emergency user
+        self.assertEqual(repr(NullUnrestrictedUser()),
+                         "<NullUnrestrictedUser (None, None)>")
+        self.assertEqual(repr(nobody),
+                         "<SpecialUser 'Anonymous User'>")
+        self.assertEqual(repr(system),
+                         "<UnrestrictedUser 'System Processes'>")
 
 def test_suite():
     suite = unittest.TestSuite()