Re: [PATCH v2 0/5] Add device DM163 (led driver, matrix colors shield & display)

[Thomas Huth]

On 28/02/2024 12.31, Inès Varhol wrote:
> This device implements the IM120417002 colors shield v1.1 for Arduino
> (which relies on the DM163 8x3-channel led driving logic) and features
> a simple display of an 8x8 RGB matrix. This color shield can be plugged
> on the Arduino board (or the B-L475E-IOT01A board) to drive an 8x8
> RGB led matrix. This RGB led matrix takes advantage of retinal persistance
> to seemingly display different colors in each row.
>
>
>
> I'm stuck on some issues with this implementation :
>
> 1. Tests
>
> TLDR: how can I provide a test or an example?
>
> I've tested the display by running custom executables and
> comparing to the result on the real board, but I don't
> know how to test it using a QTest.
>
> `qtest_init_internal` sets `-display none`
> so there's no way to test the display visually.
>
> There's no `visit_type_*` for arrays so accessing the DM163
> buffer to check its content is complicated. I could technically
> access all the elements in the array (returning a different element
> each time in the getter for example), but that seems sketchy.

I'd suggest to try to take a screenshot via QMP or HMP. If you need a third 
party binary to get something on the screen, it's maybe best to write an 
avocado test instead of a qtest. See for example 
tests/avocado/machine_m68k_nextcube.py - it takes a screenshot and then 
converts the console messages from it via Tessaract to text and looks for 
the expected strings there. Alternatively, have a look at 
tests/avocado/machine_s390_ccw_virtio.py - it boots a Linux in the guest 
that writes a string into the /dev/fb0 framebuffer, then takes a screendump 
and then tries to find the string in the file. The latter could maybe also 
be done via a qtest if you know how to set up the framebuffer without a 
guest kernel.

 HTH,
  Thomas