Register ISO 7064 mod 97-10 checksum for BA, not BT (#264) (#292)

Author: CedricConday

CHANGELOG.rst

@@ -5,6 +5,14 @@ Changelog
 
 Versions follow `CalVer <http://www.calver.org/>`_ with the scheme ``YY.0M.Micro``.
 
+Unreleased
+----------
+Fixed
+~~~~~
+* Registered the ISO 7064 mod 97-10 national checksum algorithm for Bosnia and
+  Herzegovina (``BA``) instead of ``BT`` (Bhutan, which has no IBAN), so the
+  national checksum of ``BA`` IBANs is now validated (#264).
+
 `2026.03.0`_ - 2026/03/04
 -------------------------
 Added

schwifty/checksum/iso7064_mod97_10.py

@@ -1,13 +1,13 @@
 from schwifty import checksum
 
 
-# Bosnia and Herzegovina (BT)
+# Bosnia and Herzegovina (BA)
 # Montenegro (ME)
 # North Macedonia (MK)
 # Portugal (PT)
 # Serbia (RS)
 # Slovenia (SI)
 # East Timor (TL)
-@checksum.register("BT", "ME", "MK", "PT", "RS", "SI", "TL")
+@checksum.register("BA", "ME", "MK", "PT", "RS", "SI", "TL")
 class DefaultAlgorithm(checksum.ISO7064_mod97_10):
     name = "default"

tests/test_bban.py

@@ -15,6 +15,13 @@ def test_validate_national_checksum() -> None:
     with pytest.raises(InvalidBBANChecksum):
         BBAN("BE", "539007547035").validate_national_checksum()
 
+    # Bosnia and Herzegovina (BA) uses ISO 7064 mod 97-10; it was previously
+    # registered under the wrong country code "BT" (#264), so the national
+    # checksum was never validated.
+    assert BBAN("BA", "1290079401028494").validate_national_checksum() is True
+    with pytest.raises(InvalidBBANChecksum):
+        BBAN("BA", "1290079401028400").validate_national_checksum()
+
 
 @pytest.mark.parametrize("country_code", ["DE", "ES", "GB", "FR", "PL"])
 def test_random(country_code: str) -> None: