raise a TypeError is an object of the wrong type is added to a contai…

…ner.

neo/core/container.py

@@ -342,8 +342,22 @@ def _get_container(self, cls):
     def add(self, *objects):
         """Add a new Neo object to the Container"""
         for obj in objects:
-            container = self._get_container(obj.__class__)
-            container.append(obj)
+            if (
+                obj.__class__.__name__ in self._child_objects
+                or (
+                    hasattr(obj, "proxy_for")
+                    and obj.proxy_for.__name__ in self._child_objects
+                )
+            ):
+                container = self._get_container(obj.__class__)
+                container.append(obj)
+            else:
+                raise TypeError(
+                    f"Cannot add object of type {obj.__class__.__name__} "
+                    f"to a {self.__class__.__name__}, can only add objects of the "
+                    f"following types: {self._child_objects}"
+                )
+
 
 
     def filter(self, targdict=None, data=True, container=False, recursive=True,

neo/core/group.py

@@ -76,6 +76,9 @@ def __init__(self, objects=None, name=None, description=None, file_origin=None,
             self.allowed_types = None
         else:
             self.allowed_types = tuple(allowed_types)
+            for type_ in self.allowed_types:
+                if type_.__name__ not in self._child_objects:
+                    raise TypeError(f"Groups can not contain objects of type {type_.__name__}")
 
         if objects:
             self.add(*objects)
@@ -140,8 +143,7 @@ def add(self, *objects):
             if self.allowed_types and not isinstance(obj, self.allowed_types):
                 raise TypeError("This Group can only contain {}, but not {}"
                                 "".format(self.allowed_types, type(obj)))
-            container = self._get_container(obj.__class__)
-            container.append(obj)
+        super().add(*objects)
 
     def walk(self):
         """

neo/test/coretest/test_block.py

@@ -23,7 +23,7 @@
 from neo.core import SpikeTrain, AnalogSignal, Event
 from neo.test.tools import (assert_neo_object_is_compliant,
                             assert_same_sub_schema)
-from neo.test.generate_datasets import random_block, simple_block
+from neo.test.generate_datasets import random_block, simple_block, random_signal
 
 
 N_EXAMPLES = 5
@@ -493,6 +493,10 @@ def test_add(self):
         new_blk.add(*blk.segments)
         assert len(new_blk.segments) == n_segs_start + len(blk.segments)
 
+    def test_add_invalid_type_raises_Exception(self):
+        new_blk = Block()
+        self.assertRaises(TypeError, new_blk.add, random_signal())
+
 
 if __name__ == "__main__":
     unittest.main()

neo/test/coretest/test_group.py

@@ -15,6 +15,7 @@
 from neo.core.segment import Segment
 from neo.core.view import ChannelView
 from neo.core.group import Group
+from neo.core.block import Block
 
 
 class TestGroup(unittest.TestCase):
@@ -91,3 +92,9 @@ def test_walk(self):
         target.extend([children[1], children[2], *grandchildren[2]])
         self.assertEqual(flattened,
                          target)
+
+    def test_add_invalid_type_raises_Exception(self):
+        group = Group()
+        self.assertRaises(TypeError, group.add, Block())
+
+        self.assertRaises(TypeError, Group, allowed_types=[Block])

neo/test/coretest/test_segment.py

@@ -669,6 +669,10 @@ def test_add(self):
         seg.add(proxy_epoch)
         assert len(seg.epochs) == 1
 
+    def test_add_invalid_type_raises_Exception(self):
+        seg = Segment()
+        self.assertRaises(TypeError, seg.add, Block())
+
 
 if __name__ == "__main__":
     unittest.main()