Remove legacy fallback in light color_mode property

[epenet]

Breaking change

Not user-facing

Proposed change

Reporting color_mode as None would previously log a warning and attempt to guess the color mode from the supported colors modes.

This is no longer supported.

Needs:

• Use shorthand attributes in tasmota lights #162290
• Adjust color mode handling in esphome lights #162294
• Fix missing color_mode attribute in mqtt light #162311

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:
• Link to documentation pull request:
• Link to developer documentation pull request: Remove legacy fallback in light color_mode property #162276
• Link to frontend pull request:

Checklist

• I understand the code I am submitting and can explain how it works.
• The code change is tested and works locally.
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• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.
• Any generated code has been carefully reviewed for correctness and compliance with project standards.

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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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[Copilot]

Pull request overview

This PR removes the legacy fallback behavior in the light component's color_mode property. Previously, when color_mode was None, the code would log a warning and attempt to guess the appropriate color mode based on supported color modes and available state attributes. Now, the system simply reports ColorMode.UNKNOWN when a light is on but doesn't report a color mode.

Changes:

• Removed the _light_internal_color_mode property that implemented the legacy fallback logic with automatic color mode detection
• Simplified state_attributes to directly set color_mode to ColorMode.UNKNOWN when the light is on and color_mode returns None
• Removed the test for the deprecated warning behavior that is no longer applicable

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
homeassistant/components/light/init.py	Removed _light_internal_color_mode property and replaced its usage with a simple conditional that sets color_mode to ColorMode.UNKNOWN when light is on and color_mode is None
tests/components/light/test_init.py	Removed test test_report_no_color_mode that was testing the deprecated warning and fallback behavior

Comments suppressed due to low confidence (1)

tests/components/light/test_init.py:2386

• The removed test tested the legacy fallback behavior when color_mode is None. With the new implementation, when a light is on and color_mode returns None, the state_attributes property should set color_mode to ColorMode.UNKNOWN. Consider adding a test to verify this new behavior works correctly. The test should create a MockLightEntity with _attr_color_mode = None and _attr_is_on = True, then verify that the resulting state attributes include color_mode set to ColorMode.UNKNOWN.

        (light.ColorMode.ONOFF, {light.ColorMode.ONOFF}, False),

[jbouwh]

Perhaps we shoud add tests to ensure this is covered?

[davet2001]

Looks good to me

[epenet]

With a forced failure (see #162580) we don't have any test failure
I think this is safe to merge

[emontnemery]

Thanks, @epenet 👍