Add warning for the length of the group name

channels/layers.py

@@ -160,6 +160,11 @@ def valid_channel_name(self, name, receive=False):
         raise TypeError(self.invalid_name_error.format("Channel", name))
 
     def valid_group_name(self, name):
+        error_message = (
+            f"Group name must be less than {self.MAX_NAME_LENGTH} characters."
+        )
+        if len(name) >= self.MAX_NAME_LENGTH:
+            raise TypeError(error_message)
         if self.match_type_and_length(name):
             if bool(self.group_name_regex.match(name)):
                 return True
@@ -341,7 +346,9 @@ async def group_add(self, group, channel):
         Adds the channel name to a group.
         """
         # Check the inputs
-        assert self.valid_group_name(group), "Group name not valid"
+        assert self.valid_group_name(group), (
+            f"Group name must be" f"less than {self.MAX_NAME_LENGTH} characters."
+        )
         assert self.valid_channel_name(channel), "Channel name not valid"
         # Add to group dict
         self.groups.setdefault(group, {})
@@ -350,7 +357,9 @@ async def group_add(self, group, channel):
     async def group_discard(self, group, channel):
         # Both should be text and valid
         assert self.valid_channel_name(channel), "Invalid channel name"
-        assert self.valid_group_name(group), "Invalid group name"
+        assert self.valid_group_name(group), (
+            f"Group name must be" f"less than {self.MAX_NAME_LENGTH} characters."
+        )
         # Remove from group set
         group_channels = self.groups.get(group, None)
         if group_channels:
@@ -363,7 +372,9 @@ async def group_discard(self, group, channel):
     async def group_send(self, group, message):
         # Check types
         assert isinstance(message, dict), "Message is not a dict"
-        assert self.valid_group_name(group), "Invalid group name"
+        assert self.valid_group_name(group), (
+            f"Group name must be" f"less than {self.MAX_NAME_LENGTH} characters."
+        )
         # Run clean
         self._clean_expired()
 

tests/test_layers.py

@@ -84,3 +84,24 @@ def test_channel_and_group_name_validation(method, channel_name, expected_valid)
     else:
         with pytest.raises(TypeError):
             method(channel_name)
+
+
+@pytest.mark.parametrize(
+    "name, expected_error_message",
+    [
+        (
+            "a" * 101,
+            f"Group name must be less than {BaseChannelLayer.MAX_NAME_LENGTH} "
+            "characters.",
+        ),  # Group name too long
+    ],
+)
+def test_group_name_length_error_message(name, expected_error_message):
+    """
+    Ensure the correct error message is raised when group names
+    exceed the character limit.
+    """
+    layer = BaseChannelLayer()
+
+    with pytest.raises(TypeError, match=expected_error_message):
+        layer.valid_group_name(name)