Testing Transition Systems with Input and Output Testers

1
Testing Transition Systems with Input and Output
Testers

• Alexandre Petrenko Nina Yevtushenko
• Jia Le Huo

TestCom03, May 27th, 2003
2
Outline

• Motivation
• Basic idea
• Testing frameworks
• Queued-quiescence
• Queued-suspension
• Conclusions

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Conformance Testing
Spec
Imp
Fault model ?
Tests
Test execution
4
Input/Output Transition Systems

• Non-deterministic IOTS model of Spec and Imp
• Output of IOTS cannot be blocked basic
  assumption
• Spec and Imp are input-enabled

5
Motivating Example
?coin
?coin
!coffee
?coin
?coin
?coin
!milk
!milk
!coffee
?coin
?coin
!coffee
?coin
?coin
?coin
Spec
Imp
Quiescent trace coin coin coffee milk yields the
ioco test case
Is the test case still sound if output of Spec
cannot be blocked?
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Contradiction

• The ioco test case blocks coffee after coin
• Output of IOTS cannot be blocked basic
  assumption

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Problem Statement

• A tester not blocking output of Imp must be
  input-enabled
• An input-enabled tester usually
• has unbounded test runs
• makes choice between input and output
• Both features are not desirable in practice
• We have to define a tester that
• is input-enabled
• reaches verdict in finite steps
• never chooses between input and output

8
Basic Idea
Tester
Imp
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Queued-Quiescent Traces
!coffee
?coin
?coin
?coin
?coin
?coin
!milk
!milk
!coffee
?coin
!coffee
?coin
Imp
Spec
?coin
?coin
?coin

• For a quiescent trace ? of Spec, ??I ??O? ?
  Qqtraces(Spec)
• For input sequence ?, Qqtraceso(Spec, ?)
  includes all the output sequences in response to
  ? ?'? ? O?? ??'? ? Qqtraces(Spec)
• Qqtraces(Spec) Qqtraces(Imp) (qq-trace
  equivalent)

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Queued-Quiescence Relations

• For non-oscillating Spec and Imp, if input
  sequence ? exists such that
• Qqtraceso(Imp, ?) ? Qqtraceso(Spec, ?) ? (no
  pass)then Imp is qq-separable from Spec
• Qqtraceso(Imp, ?) Qqtraceso(Spec, ?) (?fail,
  ?pass) then Imp is qq-distinguishable from Spec
• Qqtraceso(Imp, ?) ? Qqtraceso(Spec, ?) (no
  fail)then Imp is qq-weakly-distinguishable from
  Spec
• qq-separable ? qq-distinguishable ?
  qq-weakly-distinguishable

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Test Derivation with Fault Model ?

• Given Spec and Imp, check input sequences of
  length 0, 1, 2, until a sequence is found such
  that
• qq-separates, or
• qq-distinguishes, or
• qq-weakly-distinguishes Imp from Spec, or
• the input buffer capacity k is reached
• Repeat for all Imp ? ?
• k ?

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A Finer Tester
?coin
?coin
!coffee
?coin
?coin
?coin
!milk
!milk
!coffee
?coin
?coin
!coffee
?coin
?coin
?coin
Spec
Imp
After executing the qq-test case with input coin
on Spec and Imp
The resulting IOTS can be distinguished by a
qq-test case
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Queued-Suspension Testing
qq-test case of Spec
?1
qs traces are sequences of qq traces executed by
the qq testers (?1?1i?)(?2?2j?)...(?n?nk?)
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Conclusions

• Outputs cannot be blocked basic assumption
• Testing frameworks qq and qs
• Comparison with the ioco framework
• information of Interleaving of inputs and ouputs
  are lost
• so the conformance relations are coarser than
  ioco
• but ioco testing is not applicable here
• Open questions oscillating Spec, k ?, etc

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Merci beaucoup!
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An Example
coin coin
Output queue (capacity ? 2)
Input queue (capacity ? 2)
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An example (Cntd.)
When the ioco test case below is applied to Spec
with queues
Is this test case still sound?