Validate 8-digit Australian tax file numbers properly (#284)

docs/changelog.rst

@@ -23,6 +23,8 @@ Modifications to existing flavors:
   (`gh-277 <https://github.com/django/django-localflavor/pull/277>`_)
 - Fixed Dutch NLZipCodeField field not to store empty value as a single space.
   (`gh-280 <https://github.com/django/django-localflavor/pull/280>`_)
+- Fixed validation for old Australian tax file numbers.
+  (`gh-284 <https://github.com/django/django-localflavor/pull/284>`_)
 
 Other changes:
 

localflavor/au/validators.py

@@ -99,6 +99,7 @@ class AUTaxFileNumberFieldValidator(RegexValidator):
     Validation for Australian Tax File Numbers.
 
     .. versionadded:: 1.4
+    .. versionchanged:: 1.5
     """
 
     error_message = _('Enter a valid TFN.')
@@ -118,7 +119,12 @@ def _is_valid(self, value):
         """
         # 1. Multiply each digit by its weighting factor.
         digits = [int(i) for i in list(value)]
-        weighting_factors = [1, 4, 3, 7, 5, 8, 6, 9, 10]
+
+        if len(digits) == 8:
+            weighting_factors = [10, 7, 8, 4, 6, 3, 5, 1]
+        else:
+            weighting_factors = [1, 4, 3, 7, 5, 8, 6, 9, 10]
+
         weighted = [digit * weight for digit, weight in zip(digits, weighting_factors)]
 
         # 2. Sum the resulting values.

tests/test_au/tests.py

@@ -288,6 +288,14 @@ def test_raises_error_for_invalid_tfn(self):
         validator = AUTaxFileNumberFieldValidator()
         self.assertRaises(ValidationError, lambda: validator(invalid_tfn))
 
+    def test_old_tfn(self):
+        """Test old, 8-digit TFNs."""
+        validator = AUTaxFileNumberFieldValidator()
+        old_valid_tfn = '38593474'
+        validator(old_valid_tfn)
+        old_invalid_tfn = '38593475'
+        self.assertRaises(ValidationError, lambda: validator(old_invalid_tfn))
+
 
 class AULocalFlavorAUBusinessNumberModelTests(TestCase):