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Fixed #5475 -- Added the Luhn check algorithm to django.utils.checksu…

…ms so that

localflavors don't have to reimplement it each time. Thanks, __hawkeye__.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@6569 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit 18e1f56a418290d358c5338b2d97d91256f6df5f 1 parent f20b254
@malcolmt malcolmt authored
Showing with 49 additions and 1 deletion.
  1. +22 −0 django/utils/checksums.py
  2. +27 −1 tests/regressiontests/utils/tests.py
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22 django/utils/checksums.py
@@ -0,0 +1,22 @@
+"""
+Common checksum routines (used in multiple localflavor/ cases, for example).
+"""
+
+__all__ = ['luhn',]
+
+LUHN_ODD_LOOKUP = (0, 2, 4, 6, 8, 1, 3, 5, 7, 9) # sum_of_digits(index * 2)
+
+def luhn(candidate):
+ """
+ Checks a candidate number for validity according to the Luhn
+ algorithm (used in validation of, for example, credit cards).
+ Both numeric and string candidates are accepted.
+ """
+ if not isinstance(candidate, basestring):
+ candidate = str(candidate)
+ try:
+ evens = sum([int(c) for c in candidate[-1::-2]])
+ odds = sum([LUHN_ODD_LOOKUP[int(c)] for c in candidate[-2::-2]])
+ return ((evens + odds) % 10 == 0)
+ except ValueError: # Raised if an int conversion fails
+ return False
View
28 tests/regressiontests/utils/tests.py
@@ -4,7 +4,7 @@
from unittest import TestCase
-from django.utils import html
+from django.utils import html, checksums
from timesince import timesince_tests
@@ -116,6 +116,32 @@ def test_fix_ampersands(self):
for value, output in items:
self.check_output(f, value, output)
+class TestUtilsChecksums(TestCase):
+
+ def check_output(self, function, value, output=None):
+ """
+ Check that function(value) equals output. If output is None,
+ check that function(value) equals value.
+ """
+ if output is None:
+ output = value
+ self.assertEqual(function(value), output)
+
+ def test_luhn(self):
+ f = checksums.luhn
+ items = (
+ (4111111111111111, True), ('4111111111111111', True),
+ (4222222222222, True), (378734493671000, True),
+ (5424000000000015, True), (5555555555554444, True),
+ (1008, True), ('0000001008', True), ('000000001008', True),
+ (4012888888881881, True), (1234567890123456789012345678909, True),
+ (4111111111211111, False), (42222222222224, False),
+ (100, False), ('100', False), ('0000100', False),
+ ('abc', False), (None, False), (object(), False),
+ )
+ for value, output in items:
+ self.check_output(f, value, output)
+
__test__ = {
'timesince_tests': timesince_tests,
}
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