Remote Agent for Conformance Testing of TimedAutomata

1
Remote Agent for Conformance Testing of
Timed-Automata

• Ariel Stulman stulman_at_jct.ac.il
• Simon Bloch simon.bloch_at_univ-reims.fr
• H.G. Mendelbaum mendel_at_jct.ac.il

2
Introduction

• Conformance testing is a test intended to check
  that an IUT (Implementation Under Test) adheres
  to specifications (what you see is really what
  you get).
• Finding a conformance sequence and running a
  conformance test is a well known, fully-solved
  problem.
• (see Kohavis book Switching and Finite
  Automata Theory)

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Introduction

• Conformance testing is normally conducted on an
  un-timed, locally situated IUT.
• A timed-IUT is a Mealy machine with timing
  constraints added on its state transfer function.

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Description of Problem

• The controllability problem is defined as the
  task of guaranteeing the the IUT receives the
  testers inputs in the same order that they were
  sent.
• The observability problem is defined as the task
  of identifying which output is the response to
  which input matching output to input.

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Description of Problem

• With locally placed IUT the controllability and
  observability problem dont exist (transfer times
  are assumed instant).
• Using a remote environment where transfer times
  not instantaneous, intensifies problems.

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Description of Problem

• With an un-timed IUT, solutions are readily
  available.
• Using a timed-IUT (timing of the inputs critical)
  increases the severity of the problems (transfer
  times may vary).

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Description of Problem
Observability problem in remote environment
?k1
?k
e response?
ob
Observability Problem in remote environment (is
ob the response to ?k or was there a silent
response (e) to ?k, and ob is the response to
?k1 ?)
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Proposed Solution

• Conformance testing is composed of three distinct
  stages
• generation of the testing sequence.
• conduction of the test (input stimuli and record
  t-IUTs response).
• comparison of actual, recorded results with
  expected output thus, reaching a verdict.

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Proposed Solution

• Our solution is based on the fact that these
  three stages are distinct thus, they can be
  conducted in separate locations.
• One should generate a testing sequence at a
  remote location, send it to a local agent (remote
  to the tester), log the results and send them
  back for processing.

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Proposed Solution

• Using the OSI model for information transfer over
  a network, guarantees the arrival of the agent
  and testing sequence in correct form.
• Since local testing assumes instant transfer
  times, both the controllability and observabiliy
  problems were solved.

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Proposed Solution
proposed solution (semi-local testing)
tc
ok
instant transfer time
Agent
Time
t-IUT
?k1
?k
Semi-local testing assuming instant transfer
times between local testing agent and t-IUT
(constraints (tc) placed only on timing between
inputs)
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Algorithm for testing agent
procedure testing_agent_layer begin receive
s // based on OSI reset
iut_clock //resets t-IUTs clock reset
agent_clock // resets testing agents clock
while (iltn) // s n begin while(
(tk ? sk) - (tk-1 ? sk-1) ? agent_clock)
wait input( ?k ? sk ) if (output)
log( ?k ? T output ) else log( ?k ? T e
) reset (agent_clock) end while
// on s inputs send( T ) // based on
OSI end procedure
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Closing Remarks

• We proposed a method for conducting conformance
  testing of timed-IUTs over a network.
• The method presented will always overcome
  possible controllability and observability
  problems induced by the network.

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Closing Remarks

• The relevance of our algorithm is mainly for the
  field of testing real-time machines in industry
  where trade secrets prohibit the conduction of
  the entire test in remote locations.
• In the future, we hope to build a tool that will
  allow for easy, automated remote tesing.

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THANK YOU