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Reject non-ASCII digits in card numbers #568

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Reject non-ASCII digits in card numbers #568

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b246399
Enhance card number validation with ASCII check
Mrun25 Nov 14, 2026
f5ea4e1
Test rejection of Unicode card-number digits
Mrun25 Nov 14, 2026
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2 changes: 1 addition & 1 deletion src/validators/card.py
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ def card_number(value: str, /):
(Literal[True]): If `value` is a valid generic card number.
(ValidationError): If `value` is an invalid generic card number.
"""
if not value:
if not value or not value.isascii():
return False
try:
digits = list(map(int, value))
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31 changes: 31 additions & 0 deletions tests/test_card.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,8 @@
"""Test Card."""

# standard
from collections.abc import Callable

# external
import pytest

Expand Down Expand Up @@ -57,6 +60,34 @@ def test_returns_failed_on_valid_card_number(value: str):
assert isinstance(card_number(value), ValidationError)


@pytest.mark.parametrize("zero", ["\u0660", "\uff10"])
@pytest.mark.parametrize(
("validate", "value"),
[
(card_number, "4242424242424242"),
(visa, visa_cards[0]),
(mastercard, mastercard_cards[0]),
(amex, amex_cards[0]),
(unionpay, unionpay_cards[0]),
(diners, diners_cards[0]),
(jcb, jcb_cards[0]),
(discover, discover_cards[0]),
(mir, mir_cards[0]),
],
)
def test_rejects_non_ascii_card_digits(validate: Callable[[str], object], value: str, zero: str):
"""Reject Unicode digits even when an ASCII issuer prefix is retained."""
non_ascii_digit = chr(ord(zero) + int(value[-1]))
assert isinstance(validate(value[:-1] + non_ascii_digit), ValidationError)


@pytest.mark.parametrize("zero", ["\u0660", "\uff10"])
def test_rejects_all_non_ascii_card_digits(zero: str):
"""Reject a Luhn-valid card number made entirely of Unicode digits."""
value = "".join(chr(ord(zero) + int(digit)) for digit in visa_cards[0])
assert isinstance(card_number(value), ValidationError)


@pytest.mark.parametrize("value", visa_cards)
def test_returns_true_on_valid_visa(value: str):
"""Test returns true on valid visa."""
Expand Down