Autotest: "Button (Test Buttons)" FAILED for ArduPlane but is working correctly for Quadplane?

I’m developing on Win10 with Cygwin and Eclipse.
I’m currently working on a fork of ArduPlane 4.1.0dev (cloned/forked 26.03.2020 I guess).
I only changed in libraries/AP_Mission and my changes are working in SITL as expexted.
To finish I started autotest.py with different vehicles - but with unexpected results.

For ArduPlane I’v got a failure that I can’t understand:


AUTOTEST: Stopping SITL
AUTOTEST: Failing tests:
Button (Test Buttons) (Param fetch returned incorrect value (8.0) vs (0)) (see /cygdrive/c/users/willy/documents/github/buildlogs/ArduPlane-Button.txt)
FAILED STEP: fly.ArduPlane at Mon Apr 6 13:46:30 2020
Failure Summary:
fly.ArduPlane:
Button (Test Buttons) (Param fetch returned incorrect value (8.0) vs (0)) (see /cygdrive/c/users/willy/documents/github/buildlogs/ArduPlane-Button.txt)
FAILED 1 tests: [‘fly.ArduPlane’]


And in the corresponding logfile I can read:

MANUAL> Requested parameter SIM_PIN_MASK
SIM_PIN_MASK = 8.0000000
param set SIM_PIN_MASK 0.0
param fetch SIM_PIN_MASK
param set SIM_PIN_MASK 0.0
MANUAL> param fetch SIM_PIN_MASK
MANUAL> Requested parameter SIM_PIN_MASK
SIM_PIN_MASK = 0.0000000
AUTOTEST: Drained 6239 messages from mav (5044.930753/s)
AUTOTEST: FAILED: “Button (Test Buttons)”: ValueError(‘Param fetch returned incorrect value (8.0) vs (0)’,) (see /cygdrive/c/users/willy/documents/github/buildlogs/ArduPlane-Button.txt)
wp clear
wp list
wp clear
MANUAL> wp list
MANUAL> Got MAVLink msg: MISSION_ACK {target_system : 255, target_component : 0, type : 0, mission_type : 0}
Requesting 0 waypoints t=Mon Apr 6 13:42:08 2020 now=Mon Apr 6 13:42:08 2020


but for Quadplane there is no Problem:

AUTOTEST: Stopping SITL
AUTOTEST: Skipped tests:
CPUFailsafe (see servo channel values not scaled like ArduPlane)
PASSED STEP: fly.QuadPlane at Mon Apr 6 14:24:39 2020
check step: fly.QuadPlane


So I’m a little astonished and have no idea how to fix that.

Where can I see and understand what that Button-autotest is testing?
Is there a documentation about that tests in autotest where I could read?
So could anybody give me a hint how to proceed?
Or should I post that question in the Developers-Category?
(That’s my first contribution - so I feel a little insecure) :thinking:

Here is the logfile:
ArduPlane-Button.txt (10.6 KB)

In the meantime I found the test-routine in common.py - but I’m still not understanding what is the rootcause of the error.
Is it a timing-problem? on windows?