TACCLE: A Methodology for ObjectOriented Software Testing at the Class and Cluster Levels - PowerPoint PPT Presentation

Title: TACCLE: A Methodology for ObjectOriented Software Testing at the Class and Cluster Levels


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TACCLE A Methodology for Object-Oriented
Software Testing at the Class and Cluster Levels
ACM TOSEM 2001 H. Y. Chen, T. H. Tse and T. Y.
Chen

• 2002 / 7 / 2
• Heui-Seok Seo

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Contents

• Introduction
• Class Level Testing
• Algebraic Specification
• Definitions of Term Equivalence
• Testing with Equivalent Terms
• Testing with Nonequivalence Terms
• Cluster Level Testing
• Contract Specification
• Testing for Message Passing
• Conclusion

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Introduction (1/2)

• Testing Levels in OO Software
• Algorithmic Level
• The code for each operation (method) in a class
• Class Level
• The interactions of methods and data that are
  encapsulated within a given class
• Cluster Level
• The interactions among cooperating classes, which
  are grouped to accomplish some tasks
• System Level
• All the clusters

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Introduction (2/2)

• OO Testing
• Testing at the algorithmic and system levels
• It is similar to conventional program testing
• Testing at the class and cluster levels
• There is no predefined execution order in the
  class level
• Relatively little study has been made on
  cluster-level testing
• TACCLE (Testing At the Class and Cluster LEvels)
• Class Level Testing
• Using algebraic specification
• Cluster Level Testing
• Using contract specification

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Overview of Class Level Testing

• If (1) is equivalent then (2) is equivalent
  TOSEM 98
• If (1) is nonequivalent then (2) is nonequivalent

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Algebraic Specification (1/3)

• Example of Algebraic Specification

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Algebraic Specification (2/3)

• Terminology for Operations
• Creator
• Return initial object of class
• e.g. new
• Constructor
• Transform the states of the object and cannot be
  eliminated from a term by applying any rewriting
  rule
• e.g. _.push(N)
• Transformer
• Transform the states of the object but can be
  eliminated from a term by applying rewriting
  rules
• e.g. _.pop
• Observer
• Return the values of the attributes of the object
• e.g. _.isEmpty, _.top

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Algebraic Specification (3/3)

• Terminology for Sequences of Operations
• Term
• A sequence of operations
• e.g. new.push(N).push(20),pop
• Ground Term
• Term without variables (and with actual data)
• e.g. new.push(10).push(20).pop
• Normal Ground Term
• Term which cannot be transformed by any axiom
• e.g. (new.push(10).push(20).pop ? new.push(10))
• Observable Context on a class C
• Sequence of constructors or transformer followed
  by an observer of a class C
• e.g. push(10).push(20).pop.top

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Definitions of Equivalence (1/3)

• Rewriting Relations (u1 ? u2)
• For two terms u1 and u2, u1 can be transformed
  into u2 using the axioms
• Normal Equivalence (u1 nor u2)
• u1 and u2 can be transformed into the same normal
  form
• Observational Equivalence (u1 obs u2)
• For any observable context oc in the class C,
  u1.oc and u2.oc are observationally equivalent
• Attributive Equivalence (u1 att u2)
• For any observer ob in the class C, u1.ob and
  u2.ob are observationally equivalent

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Definitions of Equivalence (2/3)

• Subsumption Relation for Equivalence

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Definitions of Equivalence (3/3)

• Examples
• (Normal Equivalence) ? ?(Rewriting Relation)
• u1 new.push(10).push(20).pop
• u2 new.push(30).pop.push(10)
• (Observational Equivalence) ? ?(Normal
  Equivalence)
• u1 new(John).credit(1000).debit(200)
• u2 new(John).credit(800)
• There is not the axiom A.credit(N).debit(M) ?
  A.credit(N-M)
• (Attributive Equivalence) ? ?(Observational
  Equivalence)
• u1 new.push(10).push(20)
• u2 new.push(30).push(20)

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Testing with Equivalence (1/2)

• Equivalence Criterion
• For any observationally equivalent ground term u1
  and u2, ? (u1) and ? (u2) must be
  observationally equivalent
• ? (u) denote the object produced by the method
  sequence corresponding to a ground term u

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Testing with Equivalence (2/2)

• Test Cases Generation
• Test Case
• Fundamental fairs which are transformed from the
  same normal form
• Generation Algorithm
• Construct all patterns of normal forms from the
  creators and constructors
• S new.push(N0)
• For each axioms, replace each occurrence of
  variables with these patterns
• a4 S.push(N).pop S
• new.push(N0).push(N).pop new.push(N0)
• Randomly select an element from subdomains
• new.push(10).push(20).pop new.push(10)

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Definitions of Nonequivalence

• Subsumption Relation for Nonequivalence

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Testing with Nonequivalence (1/2)

• Nonequivalence Criterion
• For any observationally nonequivalent ground term
  u1 and u2, ? (u1) and ? (u2) must be
  observationally nonequivalent

u1 and u2 Attributive Nonequivalence Attributiv
e Nonequivalence Observational Nonequivalence
? (u1) and ? (u2) Attributive
Nonequivalence Observational Nonequivalence
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Testing with Nonequivalence (2/2)

• Test Cases Generation
• Test Cases
• Attributively nonequivalent ground terms
• Generation Algorithm
• Construct a state-transition diagram based in the
  specification
• For each node ni, find a path pi from the initial
  node n0 to ni
• n0 Initial Node
• ni nodes in state-transition diagram (i 1 ..
  k)
• Take the k(k-1)/2 pairs of attributively
  nonequivalent terms (ui, uj)
• Two terms corresponding to two paths from node n0
  to the different nodes ni and nj must be
  attributively nonequivalent

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Nonequivalence Testing Example (1/3)

• Given Specification and Implementation
• Axioms in Algebraic Specification
• a1 S.push(N).height S.height 1 if S.height
  lt 10
• a2 S.push(N).top N if S.height lt 10
• a3 S.push(N) S if S.height 10
• a4 S.push(N).pop S if S.height lt 10
• Implementation
• Stack with size 9

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Nonequivalence Testing Example (2/3)

• State-Transition Diagram

Initial Node
push
new
push
push
empty true top nil ht 0
empty false top ? 0 ht 10
empty false top ? 0 1 ? ht ? 9
pop
pop
pop
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Nonequivalence Testing Example (3/3)

• Attributively Nonequivalent Ground Terms
• u1 new
• u21 new.push(1)
• u29 new.push(1).push(2)push(9)
• u3 new.push(1).push(2)push(9).push(10)
• Test Cases
• (u1, u21), (u1, u29), (u1, u3), (u21, u3), (u29,
  u3)
• Test Results
• ? (u29) and ? (u3) are attributively equivalent
• ? (u29) (1,2,,9, 9)
• ? (u3) (1,2,,9, 9)

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Overview of Cluster Level Testing
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Contract Specification

• Example of Contract Specification

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Cluster Level Testing

• Testing for Message Passing
• Perform class-level testing in the class sender
  and receiver
• Sender SavingAccount, Receiver CheckAccount
• Analyze a rule to find the message op(param)
  sent to the object Oreceiver
• CheckAccount lt- credit(M)
• Construct an object Orecevier and Pre_Oreceiver
  by running a sequence of operation
• newCheckAccount(John).credit(1500).writeCheck(10
  00)
• Construct object Osender by running a sequence of
  operation
• newSavingAccount(John).credit(2000).debit(300)
• Run Osender.op(Oreceiver, param) and
  Pre_Oreceiver.op(param)
• Osav.transferTo(Ochk, M)
• Pre_Ochk.credit(M)

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Conclusion and Discussion

• TACCLE Methodology Using Equivalence
• Class Level Testing
• Using equivalent ground terms
• Using nonequivalent ground terms
• Cluster Level Testing
• Automated Tools for TACCLE
• Testing without Test Oracles
• Compare two objects resulted from two equivalent
  or nonequivalent sequences
• Include expected results of tests in test cases
  for the self-test
• Minimal Probe Effects
• Use observer operation in the given class

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Assumption in Algebraic Specification

• Canonical Specification
• Every sequences of rewrites on the same ground
  term reaches a unique normal form in a finite
  number of steps
• Class C with Proper Imports
• Every oc sequence on C is of finite length and
  can be extended to a primitive oc sequence in a
  finite number of steps
• Complete Implementation