Added supplementary check for CUIT number of ar localflavor

Thanks Kevin Schaul for the initial patch.

django/contrib/localflavor/ar/forms.py

@@ -81,6 +81,7 @@ class ARCUITField(RegexField):
     default_error_messages = {
         'invalid': _('Enter a valid CUIT in XX-XXXXXXXX-X or XXXXXXXXXXXX format.'),
         'checksum': _("Invalid CUIT."),
+        'legal_type': _('Invalid legal type. Type must be 27, 20, 23 or 30.'),
     }
 
     def __init__(self, max_length=None, min_length=None, *args, **kwargs):
@@ -96,6 +97,8 @@ class ARCUITField(RegexField):
         if value in EMPTY_VALUES:
             return ''
         value, cd = self._canon(value)
+        if not value[:2] in ['27', '20', '23', '30']:
+            raise ValidationError(self.error_messages['legal_type'])
         if self._calc_cd(value) != cd:
             raise ValidationError(self.error_messages['checksum'])
         return self._format(value, cd)

tests/regressiontests/localflavor/ar/tests.py

@@ -81,6 +81,7 @@ class ARLocalFlavorTests(SimpleTestCase):
     def test_ARCUITField(self):
         error_format = ['Enter a valid CUIT in XX-XXXXXXXX-X or XXXXXXXXXXXX format.']
         error_invalid = ['Invalid CUIT.']
+        error_legal_type = [u'Invalid legal type. Type must be 27, 20, 23 or 30.']
         valid = {
             '20-10123456-9': '20-10123456-9',
             '20-10123456-9': '20-10123456-9',
@@ -94,8 +95,9 @@ class ARLocalFlavorTests(SimpleTestCase):
             '210123456-9': error_format,
             '20-10123456': error_format,
             '20-10123456-': error_format,
-             '20-10123456-5': error_invalid,
-             '27-10345678-1': error_invalid,
-             '27-10345678-1': error_invalid,
+            '20-10123456-5': error_invalid,
+            '27-10345678-1': error_invalid,
+            '27-10345678-1': error_invalid,
+            '11211111110': error_legal_type,
         }
         self.assertFieldOutput(ARCUITField, valid, invalid)