Add workaround for Sparkasse Heidelberg

fints/client.py

@@ -17,7 +17,8 @@
 from .formals import (
     CUSTOMER_ID_ANONYMOUS, KTI1, BankIdentifier, DescriptionRequired,
     SynchronizationMode, TANMediaClass4, TANMediaType2,
-    SupportedMessageTypes)
+    SupportedMessageTypes, TANUsageOption
+)
 from .message import FinTSInstituteMessage
 from .models import SEPAAccount
 from .parser import FinTS3Serializer
@@ -1414,8 +1415,13 @@ def get_tan_media(self, media_type = TANMediaType2.ALL, media_class = TANMediaCl
             context = self._get_dialog()
             method = lambda dialog: dialog.send
 
-
         with context as dialog:
+            if isinstance(self.init_tan_response, NeedTANResponse):
+                # This is a workaround for when the dialog already contains return code 3955.
+                # This occurs with e.g. Sparkasse Heidelberg, which apparently does not require us to choose a
+                # medium for pushTAN but is totally fine with keeping "" as a TAN medium.
+                return TANUsageOption.ALL_ACTIVE, []
+
             hktab = self._find_highest_supported_command(HKTAB4, HKTAB5)
 
             seg = hktab(

fints/utils.py

@@ -300,6 +300,11 @@ def minimal_interactive_cli_bootstrap(client):
         m = client.get_tan_media()
         if len(m[1]) == 1:
             client.set_tan_medium(m[1][0])
+        elif len(m[1]) == 0:
+            # This is a workaround for when the dialog already contains return code 3955.
+            # This occurs with e.g. Sparkasse Heidelberg, which apparently does not require us to choose a
+            # medium for pushTAN but is totally fine with keeping "" as a TAN medium.
+            client.selected_tan_medium = ""
         else:
             print("Multiple tan media available. Which one do you prefer?")
             for i, mm in enumerate(m[1]):