klipper stringing test with firmware retraction

Activate firmware retraction in your slicer.
Activate firmware retraction in klipper :

[firmware_retraction]
retract_length: 0.8
retract_speed: 60
unretract_extra_length: 0
unretract_speed: 60

Slice the test.
Print it and at the start of the print execute this command in the terminal :
TUNING_TOWER COMMAND=SET_RETRACTION PARAMETER=RETRACT_LENGTH START=0 FACTOR=0.05

this test will test retract length from 0 to 5