fix b4w real-world import

tests/test_model_b4wexport.py

@@ -33,6 +33,27 @@ def test_b4w_export_account_iban_to_short():
         _ = B4wExportFactory.build(OwnrAcctIBAN="DE123")
 
 
+def test_b4w_export_other_iban_empty_is_none():
+    data = B4wExportFactory.build(RmtdAcctIBAN="")
+    assert data.other_iban is None
+
+
+def test_b4w_export_other_iban_blank_is_none():
+    data = B4wExportFactory.build(RmtdAcctIBAN="   ")
+    assert data.other_iban is None
+
+
+def test_b4w_export_other_iban_invalid():
+    with pytest.raises(ValidationError):
+        _ = B4wExportFactory.build(RmtdAcctIBAN="not an IBAN")
+
+
+def test_b4w_export_other_iban_repr_round_trip_empty():
+    data = B4wExportFactory.build(RmtdAcctIBAN="")
+    data2 = eval(str(data))
+    assert data == data2
+
+
 def test_b4w_export_parameters_to_dict():
     data = B4wExportFactory.build()
     params = data.parameters_to_dict()