Check that FinTS3Segments only have DE or DEG fields

Author: henryk

fints/segments/__init__.py

@@ -1,12 +1,26 @@
 import re
 
-from fints.formals import Container, SegmentHeader, DataElementGroupField, DataElementField, ReferenceMessage, SegmentSequenceField, SecurityProfile, SecurityIdentificationDetails, SecurityDateTime, EncryptionAlgorithm, KeyName, Certificate, HashAlgorithm, SignatureAlgorithm, UserDefinedSignature, Response
+from fints.formals import Container, ContainerMeta, SegmentHeader, DataElementGroupField, DataElementField, ReferenceMessage, SegmentSequenceField, SecurityProfile, SecurityIdentificationDetails, SecurityDateTime, EncryptionAlgorithm, KeyName, Certificate, HashAlgorithm, SignatureAlgorithm, UserDefinedSignature, Response
 
 from fints.utils import classproperty, SubclassesMixin
 
 TYPE_VERSION_RE = re.compile(r'^([A-Z]+)(\d+)$')
 
-class FinTS3Segment(Container, SubclassesMixin):
+class FinTS3SegmentMeta(ContainerMeta):
+    @staticmethod
+    def _check_fields_recursive(instance):
+        for name, field in instance._fields.items():
+            if not isinstance(field, (DataElementField, DataElementGroupField)):
+                raise TypeError("{}={!r} is not DataElementField or DataElementGroupField".format(name, field))
+            if isinstance(field, DataElementGroupField):
+                FinTS3SegmentMeta._check_fields_recursive(field.type)
+
+    def __new__(cls, name, bases, classdict):
+        retval = super().__new__(cls, name, bases, classdict)
+        FinTS3SegmentMeta._check_fields_recursive(retval)
+        return retval
+
+class FinTS3Segment(Container, SubclassesMixin, metaclass=FinTS3SegmentMeta):
     header = DataElementGroupField(type=SegmentHeader)
 
     @classproperty

tests/test_models.py

@@ -10,6 +10,24 @@ def test_metaclass_foo():
     assert list(a._fields) == ['header', 'message_size', 'hbci_version', 'dialogue_id', 'message_number', 'reference_message']
     assert a._fields['header']
 
+def test_fints3_only_de_and_deg():
+    from fints.formals import Field, Container, DataElementGroupField, ContainerField
+
+    with pytest.raises(TypeError, match="b=.* is not DataElementField or DataElementGroupField"):
+        class Foo(FinTS3Segment):
+            a = NumericField()
+            b = Field()
+
+    class A(Container):
+        a = Field()
+
+    class B(Container):
+        b = DataElementGroupField(type=A)
+
+    with pytest.raises(TypeError, match="a=.* is not DataElementField or DataElementGroupField"):
+        class Foo(FinTS3Segment):
+            c = DataElementGroupField(type=B)
+
 def test_descriptor_subclassing():
     a = DataElementField(type='an')
     assert isinstance(a, AlphanumericField)