Raise on missing color mode

[epenet]

Proposed change

Partial reversal of #162276

As spotted in #162650, changing the default for _attr_color_mode is an unintended breaking change for "did I already initialise the color mode"

Instead of defaulting to UNKNOWN we raise an exception if the color_mode is not set

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
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[home-assistant]

Hey there @felipecrs, mind taking a look at this pull request as it has been labeled with an integration (openrgb) you are listed as a code owner for? Thanks!

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[home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (light) you are listed as a code owner for? Thanks!

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[felipecrs]

@epenet is the OpenRGB integration your only concern?

[Copilot]

Pull request overview

This PR rolls back part of #162276 by restoring the ability for LightEntity.color_mode / _attr_color_mode to be None, to avoid an unintended breaking change in default light behavior (as discussed in #162650).

Changes:

• Make LightEntity._attr_color_mode optional again and update LightEntity.color_mode return type accordingly.
• Adjust OpenRGB light attribute update logic to use None as the “unknown/unset” sentinel instead of ColorMode.UNKNOWN.
• Update the pylint type-hint enforcement plugin to allow LightEntity.color_mode to return None.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
pylint/plugins/hass_enforce_type_hints.py	Updates type-hint enforcement rules to allow LightEntity.color_mode to be optional.
homeassistant/components/openrgb/light.py	Aligns OpenRGB’s internal color mode calculation with the restored None default/semantics.
homeassistant/components/light/__init__.py	Restores None as the default/allowed value for _attr_color_mode and color_mode.

[epenet]

@epenet is the OpenRGB integration your only concern?

I am not sure.

As I have been cleaning up the deprecate features of the light platform, all other failing tests were "intended" (they raised warnings before, and now they fail).

However the openrgb was affected in a way that was not intended (working without warning => not working).
It was an easy fix, but we don't know how many custom integrations could be affected in a similar way.

[emontnemery]

As discussed yesterday, I think all light.py need to be reviewed to see if there are more cases than openrgb

[emontnemery]

I don't think this is a good change, before #162276 the light's color mode would be deduced by its attributes (brightness, color, and so on) and thus not be None. Now, the color mode will be None as I understand it?

Also, tests should be updated.

[epenet]

I don't think this is a good change, before #162276 the light's color mode would be deduced by its attributes (brightness, color, and so on) and thus not be None. Now, the color mode will be None as I understand it?

Also, tests should be updated.

As discussed on Discord, I have adjusted this to raise an error if the color_mode is still None, and added some tests accordingly.

[emontnemery]

LGTM, thanks @epenet 👍