I dont think there is any actual requirement for developers to be
available during test day.
We might have started out that way but we always planned to migrate away
from it as well as extending test days over couple of days like test
week/weekend
JBG
I've always assumed it is an implicit requirement and in my public presentations
I've always mentioned it as one of the largest advantages of attending a test day -
the ability to discuss things directly with developers.
I don't say there can't be any test days without developers presence, but in my
view, those should be really exceptional.