Fix not including device_name in friendly name if it is None

[jbouwh]

Breaking change

Not sure

Proposed change

If both device_entry.name_by_user or device_entry.name are None, then it should not be used to build the friendly name.

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[balloob]

This makes me wonder if we should even allow a device to have no name. Should we make up a random name in the device registry if name is empty?

[jbouwh]

I am not sure about that, it is that with mqtt we have some tests and examples where no device name is set, when then a default entity name is assigned we get a None prefix to the friendly name, and none_ is added to the 2nd part of the entity id. @emontnemery thinks this is a bug. In this case I would just omit the device part as it does not make sense to add it.

[balloob]

Shouldn't we reject the configuration instead? if you want to have your entity name be based on a device but there is no device name, it doesn't work ?

[jbouwh]

It does work, you get an unnamed device. Now allowing this would be breaking, as a device name is optional.

[balloob]

Right, but shouldn't we phase in that it's required if has_entity_name is set to True?

[jbouwh]

That sounds reasonable to me. If if for MQTT items we do not want to bother the user, we could set has_entity_name to False when no device name is set and make a device_name required when has_entity_name is set to True.

[jbouwh]

Setting has_entity_name to False if no device name is set would be a good alternative:
https://github.com/home-assistant/core/pull/95159/files#r1247719960

[jbouwh]

A case where this will not work is when we want to follow the name of the device_class. In that case has_entity_name must be set to True.

[jbouwh]

Thnx @balloob !

[jbouwh]

Reopening since the default device_name still can be None