Android apps must work correctly even if their execution is interrupted by external events. For instance, an app must work properly even if a phone call is received, or after its layout is redrawn because the smartphone has been rotated. Since these events may require destroying, when the execution is interrupted, and recreating, when the execution is resumed, the foreground activity of the app, the only way to prevent the loss of state information is to save and restore it. This behavior must be explicitly implemented by app developers, who often miss to implement it properly, releasing apps affected by data loss problems, that is, apps that may lose state information when their execution is interrupted. Although several techniques can be used to automatically generate test cases for Android apps, the obtained test cases seldom include the interactions and the checks necessary to exercise and reveal data loss faults. To address this problem, this talk presents Data Loss Detector (DLD), a test case generation technique that integrates an exploration strategy, data-loss-revealing actions, and two customized oracle strategies for the detection of data loss failures. DLD revealed 75% of the faults in a benchmark of 54 Android app releases affected by 110 known data loss faults, and also revealed unknown data loss problems, outperforming competing approaches. Video https://www.youtube.com/watch?v=s6XZ7F8L3nY Paper https://arxiv.org/abs/2010.05584

1. Data Loss Detector:
Automatically Revealing Data Loss Bugs in
Android Apps
Oliviero Riganelli
University of Milano Bicocca
joint work with
Simone Paolo Mottadelli, Claudio Rota, Daniela Micucci and Leonardo Mariani
Distinguished Artifact

2. Recreating Android Activity
Running
(visible)
Destroyed
Created
Running
(visible)
create activity restore activity state
save activity state1
2 3

3. https://disco.unimib.it
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Instance State
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Recreating an Activity

4. https://disco.unim
ib.it
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………….Running
(visible)
Destroyed
save activity state1
https://disco.unimib.it
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Instance State
Recreating an Activity

5. https://disco.unimib.it
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Created
create activity2
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Instance State
Recreating an Activity

6. https://disco.unimib.it
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Created
Running
(visible)
restore activity state3
Instance State
Recreating an Activity

7. https://disco.unimib.it
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Data Loss
Instance State
https://disco.unimib.it
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8. https://disco.unim
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Running
(visible)
Destroyed
save activity state1
https://disco.unimib.it
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Data Loss
Instance State

9. https://disco.unimib.it
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Created
create activity2
https://disco.unim
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Instance State
Data Loss

10. https://disco.unimib.it
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https://disco.unimib.it
Created
Running
(visible)
restore activity state3
Instance State
Data Loss

11. https://disco.unimib.it
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https://disco.unimib.it
Created
Running
(visible)
restore activity state3
Instance State
Data Loss
The metronome is frustrating. I
use it when I practice but if I ever
stop it, and turn off the screen, it
resets to 40bpm and 4/4 time
As soon as I opened a comic
through this app I was really happy
given its functionality and ease of
use. But everytime I rotate the
screen, the app exits saying " file
could not be loaded"
Randomly sets back to 100% and
auto brightness after using camera

12. Pervasiveness of Data Loss
Problems
APP APP APP APP APP

13. Pervasiveness of Data Loss
Problems
88%
Apps with data loss
12%
App without data loss

14. Pervasiveness of Data Loss
Problems
88%
Apps with data loss
12%
App without data loss

15. Pervasiveness of Data Loss
Problems
88%
Apps with data loss
12%
App without data loss

16. Pervasiveness of Data Loss
Problems
88%
Apps with data loss
12%
App without data loss

17. Data Loss Detector (DLD)
https://disco.unimib.it
oliviero.riganelli
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https://disco.unimib.it

18. Data Loss Detector (DLD)
Touch buttons
Type text
Press HOME key
…

19. Data Loss Detector (DLD)
Touch buttons
Type text
Press HOME key
…

20. GrantPermissionsActivity
<FIRST>
GrantPermissionsActivity
TouchEvent(“ALLOW”) TouchEvent(“ALLOW”)
TouchEvent(“3”)
MainActivity
MainActivity
Launcher
KeyEvent(HOME)
GUI Model

21. TouchEvent(“3”)
GrantPermissionsActivity
<FIRST>
GrantPermissionsActivity MainActivity
MainActivity
Launcher
TouchEvent(“ALLOW”) TouchEvent(“ALLOW”)
KeyEvent(HOME)
GUI Model
GUI:
ACTIONS: KeyEvent(HOME)
TouchEvent(“ALLOW”)
…
STATE

22. TouchEvent(“3”)
GrantPermissionsActivity
<FIRST>
GrantPermissionsActivity MainActivity
MainActivity
Launcher
TouchEvent(“ALLOW”) TouchEvent(“ALLOW”)
KeyEvent(HOME)
GUI Model
Type: Touch
View:
Command: adb shell input …
EVENT

23. https://disco.unimib.it
oliviero.riganelli
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Data Loss Detector (DLD)
oliviero.riganelli
Love is the answer
Biased Model-Based Exploration
Data Loss Oracles
Data-Loss-Revealing Actions

24. TouchEvent(“OK”)
Sn
TouchEvent(“NO THANKS”)
KeyEvent(MENU)
Biased Model-Based Exploration

25. Sn
KeyEvent(MENU)
Biased Model-Based Exploration
90% Unexecuted event 10% Any event
TouchEvent(“OK”)
TouchEvent(“NO THANKS”)

26. Sn
KeyEvent(MENU)
Biased Model-Based Exploration
P:0.333
P:0.333
P:0.333
90% Unexecuted event 10% Any event
TouchEvent(“OK”)
TouchEvent(“NO THANKS”)

27. Sn
KeyEvent(MENU)
Biased Model-Based Exploration
P:0.333
P:0.333
P:0.333
90% Unexecuted event 10% Any event
TouchEvent(“OK”)
TouchEvent(“NO THANKS”)

28. Sn
KeyEvent(MENU)
Biased Model-Based Exploration
P:0.033
P:0.483
P:0.483
90% Unexecuted event 10% Any event
TouchEvent(“OK”)
TouchEvent(“NO THANKS”)

29. Sn
KeyEvent(MENU)
Biased Model-Based Exploration
90% Unexecuted event 10% Any event
TouchEvent(“OK”)
TouchEvent(“NO THANKS”)
P:0.033
P:0.483
P:0.483

30. Sn
KeyEvent(MENU)
Biased Model-Based Exploration
P:0.033
P:0.933
P:0.033
90% Unexecuted event 10% Any event
TouchEvent(“OK”)
TouchEvent(“NO THANKS”)

31. Data-Loss-Revealing Actions
NEW STATE
Systematic
Probabilistic
ALREADY VISITED STATE

32. Systematic data-loss-revealing action
https://
oliviero.riganelli
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33. Systematic data-loss-revealing action
https://
oliviero.riganelli
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https://disco.unimib.it
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https://
oliviero.riganelli
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34. https://
oliviero.riganelli
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https://disco.unimib.it
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https://
oliviero.riganelli
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https://
oliviero.riganelli
…
…
…
…
.
https://disco.unim
ib.it
Systematic data-loss-revealing action

35. Probabilistic data-loss-revealing actionhttps://
oliviero.rig
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https://
oliviero.rig
…
…
…
…
.
https://
oliviero.riganelli
…
…
…
…
.
https://
oliviero.rig
…
…
…
…
.
https://
oliviero.riganelli
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…
…
…
.

36. Data Loss Oracles
[
…
{
'content_description': None,
'resource_id': None,
'text': 'Editing "test123"',
'visible': True,
'checkable': False,
'children': [],
'size': '720*81',
'checked': False,
'temp_id': 4,
'selected': False,
'child_count': 0,
...
}
...
]
Snapshot-based oracle Property-based oracle

37. Data Loss Oracles
Snapshot
Property
…
‘content_description':
…
…
‘content_description':
...
Before double rotation After double rotation

38. Data Loss Oracles
Snapshot
Property
…
‘content_description':
'Open navigation
drawer',
…
…
‘content_description':
‘Close navigation
drawer',
...
Before double rotation After double rotation

39. EvaluationEvaluation
Research Questions
APPs
Configuration
Google Nexus 5
Android 6.0
RQ0 - What is the ε that provides the best
exploration?
RQ1 - How effective is DLD with data
loss problems?
RQ2 - Is DLD more effective than state-
of-the-art techniques?
RQ3 - What is the tradeoff between the
snapshot- and property- based oracles?
RQ4 - Are data loss faults relevant to
developers?
110 real data loss
54 app releases
Riganelli et al. "A Benchmark of Data Loss Bugs for
Android Apps”, MSR 2019.

40. RQ1 - How effective is DLD
with data loss problems?
110
Benchmark Data Loss

41. RQ1 - How effective is DLD
with data loss problems?
27 83 267
Benchmark Data Loss Detected by DLD

42. RQ1 - How effective is DLD
with data loss problems?
27 83 267
Benchmark Data Loss Detected by DLD
90% of faults confirmed by
developers, see RQ4 in the paper

43. RQ2 - Is DLD more effective
than state-of-the-art techniques?
0
50
100
150
200
Faulty Activity Benchmark Faults New Faults Spuriuos Violations
Alaric DLD

44. RQ2 - Is DLD more effective
than state-of-the-art techniques?
0
50
100
150
200
Faulty Activity Benchmark Faults New Faults Spuriuos Violations
Alaric DLD
COMPARISON TO QUANTUM
IN THE PAPER

45. RQ3 - What is the tradeoff between the
snapshot- and property- based oracles?
73%
18%
9%
snapshot-based oracle property-based oracle
both incomplete rotation
74%
21%
5%
Data loss detected Spurious oracle violations

46. https://github.com/datalossdetector/DLD
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