TGV: theory, principles and algorithms · TGV: theory, principles and algorithms David Reisenberger Basics TGV overview IOLTS Formal test purposes Principles and algorithms Synchronous

TGV: theory,principles andalgorithms

DavidReisenberger

BasicsTGV overviewIOLTSFormal testpurposes

Principles andalgorithmsSynchronousproductExtractingvisible behaviourTest selectionControllabilityOn-The-Flysynthesis

The Tool

Conclusion

TGV: theory, principles and algorithms

David Reisenberger

May 31, 2012


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The paper

Claude Jard, Thierry Jeron

Published online 2004, Springer-Verlag


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TGV

Test generation with verification technology

automatic synthesis of conformance test cases from aformal specification of a (non-deterministic) reactivesystem

”on-the-fly” synthesis


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Outline

1 BasicsTGV overviewIOLTSFormal test purposes

2 Principles and algorithmsSynchronous productExtracting visible behaviourTest selectionControllabilityOn-The-Fly synthesis

3 The Tool

4 Conclusion


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Definitions

Test case: testing particular functionality

Test suite: a set of tests

Test: outputs are stimuli for IUT, inputs are observationsof IUT’s outputs

Fail verdict: IUT is rejected

Pass verdict: IUT is accepted

Inconclusive verdict: correct behaviour is observed buttest purpose can’t be reached

Soundness: test cases only reject non-conformant IUT’s

Exhaustiveness: all non-conformant IUT’s are rejected


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Functional view


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IOLTS

M = (QM ,AM ,!M , qM0 )AM = AMI [ AMO [ IM

a(i) 2 AM \ IM

⌧(i) 2 IM

Fireable actions: �(q)

Transitions:a�!

Visible behaviour: )Input: ?a

Output: !x

det(M): M without internal actions


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IOLTS cont.


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Quiescence

Deadlock: �(q) = ;Output quiescence: �(q) ✓ AMILivelock

deadlock(M) ✓ outputlock(M)quiescent(M) = livelock(M) [ outputlock(M)


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Suspension automaton �(S)

TP SP


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det(�(S)) = SVIS


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Test purpose

TP = (QTP ,ATP ,!TP , qTP0 )AcceptTP : select target behaviour

RefuseTP : cut down specification

Allows e�cient test selection on-the-fly

Smaller than specification but complete (...?)


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Test purpose cont.

S SP


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Principles and algorithms


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Synchronous product

Mark behaviours of S by Accept,Refuse

Accepted behaviour of SP are accepted behaviours of S byTP


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S ⇥ TP = SP

S TP


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SPVIS = det(�(SP))

CTG


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Test selection

Extracting test case by selection of accepted behaviours

ACTGO ✓ AVISIACTGI = A

VISO

L2A: all states that lead to accept

Pass: AcceptVIS

Inconc: direct successors of states in L2A by output inSPVIS

Fail: else

Result: CTG (Complete Test Graph)

TGVLoop, based on Tarjan’s algo (O(n), S(n))


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Test selection

SPVIS TC


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Controllability

Extract a controllable subgraph of CTG

Get rid of choices between I/O (pruning)

This can happen during TGVLoop (partially)


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A test case

CTG


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On-The-Fly synthesis

perform lazy construction of subgraphs of S , SP , SPVIS

needed functions

initfireablesuccComparison functionFunction to compute membership of Accept/Refuse

goal: reduce size of graphs


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The Tool

Several software layersCommunicate through APIsEach one is simulation of IOLTS (allows graph traversal)Each level implements one of the algorithmsOutput: test cases in TTCN or graph formats (.aut, .bcg)Can be used to verify manually created test casesSunOS 5, Windows XP, Linux


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Architecture


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Timers


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Conclusion

TGV can synthesize tests from industrial size specs

Drawback: manual creation of test purpose

Still better than manual test case creation

Future: distributed tests, improvements of algorithms

BasicsTGV overviewIOLTSFormal test purposes

Principles and algorithmsSynchronous productExtracting visible behaviourTest selectionControllabilityOn-The-Fly synthesis

The ToolConclusion

TGV: theory, principles and algorithms · TGV: theory, principles and algorithms David Reisenberger Basics TGV overview IOLTS Formal test purposes Principles and algorithms Synchronous

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