Fix KNX rgb(w) color (again)

[farmio]

Proposed change

Calculate master brightness from color and scale up color.

As HA treats RGB as 4-channel Light (red, green, blue, brightness) we have to fake the KNX 3-channel RGB color to have brightness not applied twice. Same for RGBW.

At least I think this is how it should work. I don't have any colored lights so I can't test this live. Would be nice if anyone could test this with an actual actuator.

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[probot-home-assistant]

Hey there @Julius2342, @marvin-w, mind taking a look at this pull request as its been labeled with an integration (knx) you are listed as a codeowner for? Thanks!
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[github-actions]

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[farmio]

@spacegaier I think you have tested this. Shall we use it or close it?

[EricReiche]

Hi, how to test this?
I replaced the /usr/src/homeassistant/homeassistant/components/knx/light.py in my docker container and restarted it. Should that do the trick?
If yes, it didn't work.

[farmio]

Docker makes this more complicated. If you have mounted it as volume it may do the trick. Else it will not persist these changes after a container restart (which you need to load it). You can inspect the code in the running container from a shell or just add some print("### hello") and see if it appears in the logs.
Easier way is to install a local test environment and just check out the branch / PR via GitHub Desktop 😉

If it is loaded at least one of the rgb colors should always be 255 in developer tools -> states. At least that was the intention.

[farmio]

I did not find anyone to test this on a live system, but I still think it should be the way to go.

[bdraco]

Considering how many branches there are here, it would be good to have some tests for this so it doesn't cause regressions for other light types.

[farmio]

I'm just working on writing tests for the knx light module... will take some time - so many possible configurations 🤪

[farmio]

Done. I'll rebase this when #58912 is merged.

[marvin-w]

Looks good! Thanks

[epenet]

Looks like a flaky test: https://github.com/home-assistant/core/runs/4216637595?check_suite_focus=true

[epenet]

Actually it's more than flaky: it fails everytime on my machine:

FAILED tests/components/knx/test_light.py::test_light_rgbw_individual[pyloop] - AssertionError: assert 'on' == 'off'

Results (3.90s):
      44 passed
       1 failed
         - tests/components/knx/test_light.py:620 test_light_rgbw_individual[pyloop]

[marvin-w]

I guess this is a side effect from the library bump. On it.

[marvin-w]

#59748