Capture and rep

1. Introduction
Overview
Static devices
Dynamic behaviour
Capture and Replay Hardware behaviour
for Regression Testing and Useful Bug Reports
Martin Pitt
<martin.pitt@ubuntu.com>
Linux Plumbers Conference, September 2013
Conclusion

2. Introduction
Overview
Static devices
Dynamic behaviour
Conclusion
Motivation
From: Joe User <joe@random.com>
Subject: eye phone 17 doesn’t work after Ubuntu upgrade
My eye phone 17 has worked fine in Ubuntu 12.04 LTS, but under 13.04
Rhythmbox doesn’t do anything any more when I plug it in.
From: Jack Developer <hacker@freedesktop.org>
Subject: Re: eye phone 17 doesn’t work after Ubuntu upgrade
Sorry, I don’t have this device. It works fine with my phone and media
player. Can you please attach the output of ”rhythmbox –debug”?

3. Introduction
Overview
Static devices
Dynamic behaviour
Conclusion
Structure
• umockdev-record /dev/ttyUSB0
• UMockdevTestbed GObject class API
• umockdev-run --device 3g-usbstick.umockdev
--script /dev/ttyUSB0=connect.script ModemManager

4. Introduction
Overview
Static devices
Dynamic behaviour
How does it look like?
Live demo, brace for impact!
Conclusion

5. Introduction
Overview
Static devices
Dynamic behaviour
Device detection only
• only sysfs, udev props, uevents
• no /dev access
• power supply devices (upower), lsusb, DMI, rfkill,
/sys/class/drm/
Conclusion

6. Introduction
Overview
Static devices
Dynamic behaviour
Conclusion
API usage: create device
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UMockdevTestbed ∗ t e s t b e d = u m o c k d e v t e s t b e d n e w ( ) ;
const char ∗ sys bat = umockdev testbed add device ( testbed ,
” p o w e r s u p p l y ” , ” fakeBAT0 ” , NULL ,
/∗ a t t r i b u t e s ∗/
” type ” , ” Battery ” ,
” status ” , ” Discharging ” ,
” e n e r g y f u l l ” , ” 60000000 ” ,
” e n e r g y n o w ” , ” 48000000 ” ,
NULL ,
/∗ p r o p e r t i e s ∗/
”POWER SUPPLY ONLINE” , ” 1 ” ,
NULL ) ;
);
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/∗ s t a r t GTestDBus and upowerd ∗/
/∗ c a l l upower −−dump o r q u e r y o v e r D−BUS ∗/

7. Introduction
Overview
Static devices
Dynamic behaviour
API usage: load device
umockdev-record /sys/class/power supply/BAT0 >
bat0.umockdev
Load with:
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from g i . r e p o s i t o r y i m p o r t UMockdev
t e s t b e d = UMockdev . T e s t b e d . new ( )
t e s t b e d . a d d f r o m f i l e ( t e s t b e d , ’ b a t 0 . umockdev ’ )
Conclusion

8. Introduction
Overview
Static devices
Dynamic behaviour
API usage: change device
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/∗ c h a n g e b a t t e r y c h a r g e ∗/
umockdev testbed set attribute ( testbed , sys bat ,
” e n e r g y n o w ” , ” 1500000 ” ) ;
/∗ s e n d u e v e n t t o n o t i f y upowerd ∗/
u m o c k d e v t e s t b e d u e v e n t ( t e s t b e d , s y s b a t , ” change ” ) ;
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/∗ c a l l upower −−dump o r q u e r y o v e r D−BUS ∗/
Conclusion

9. Introduction
Overview
Static devices
Dynamic behaviour
Implementation: preload library
$ umockdev-wrapper ./my-test-suite
or
$ LD PRELOAD=libumockdev-preload.so ./my-test-suite
Conclusion

10. Introduction
Overview
Static devices
Dynamic behaviour
/dev emulation
$UMOCKDEV DIR/dev/*
Common cases:
• char device (tty, ModemManager, evdev events): read(),
write()
• socket (Android rild): send(), recv()
• ioctl (usbdevfs, evdev properties)
• block device
Conclusion

11. Introduction
Overview
Static devices
Dynamic behaviour
read/write scripts
w 0 ATZ^J
r 200 OK^J
w 350 ATI0^J
r 10 Huawei X1234^Jcaps:^I2G 3G 4G^J
[...]
f 5 w 50 ^@jf9j#2j(*J^@^@^@
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G E r r o r ∗ e r r o r = NULL ;
u m o c k d e v t e s t b e d l o a d s c r i p t ( t e s t b e d , ” / d e v / ttyUSB0 ” ,
” h u a w e i . s c r i p t ” , &e r r o r ) ;
Conclusion

12. Introduction
Overview
Static devices
Dynamic behaviour
Conclusion
ioctl emulation
USBDEVFS_CONNECTINFO 0 0B00000000000000
USBDEVFS_REAPURB 0 1 2 0 0 8 8 0 0001020304050607
USBDEVFS_REAPURB 0 1 129 0 0 15 6 0 DEADBEEF0042
USBDEVFS_REAPURB 0 1 129 0 0 15 7 0 10090807060504
USBDEVFS_REAPURB 0 1 129 -5 0 15 5 0 1010101010
EVIOCGBIT(3) 8 0300001100806002
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G E r r o r ∗ e r r o r = NULL ;
u m o c k d e v t e s t b e d l o a d i o c t l ( t e s t b e d , ” / d e v / b u s / u s b /001/013 ” ,
”cam−i m p o r t . i o c t l ” , &e r r o r ) ;

13. Introduction
Overview
Static devices
Dynamic behaviour
Conclusion
Summary
• successful for several packages
• limited to recorded use cases, without much deviation
• use case driven, especially ioctls
• specific to /sys and /dev
• other kinds of devices: scsi debug, veth, mac80211 hwsim
• testing against D-BUS services: python-dbusmock, Bendy Bus

14. Introduction
Overview
Static devices
Dynamic behaviour
EOF
Q & A, other use cases, discussion
https://github.com/martinpitt/umockdev/
pitti on Freenode, martin.pitt@ubuntu.com
Slides license: CC-BY-SA 3.0
Conclusion