Data Flow Testing

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Data Flow Testing Define/Use Testing Winter 2006
Presented by Nikos Giannopoulos nikos_at_swen.uwaterl
oo.ca
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Agenda

• Define/Use Testing Definitions
• Define/Use Testing Example
• Commission Problem
• DU-Path Test Coverage Metrics

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Agenda

• Define/Use Testing Definitions
• Define/Use Testing Example
• Commission Problem
• DU-Path Test Coverage Metrics

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Define/Use Testing Definitions

• Node is a defining node of the
  variable , written as DEF(v,n), iff the
  value of the variable v is defined at the
  statement fragment corresponding to node n
• Node is a usage node of the
  variable , written as USE(v,n), iff the
  value of the variable v is used at the statement
  fragment corresponding to node n
• A usage node USE(v,n) is a predicate use (denoted
  as P-use, outdegree 2) iff the statement n is a
  predicate statement otherwise USE(v,n) is a
  computation use (denoted C-use, outdegree 1)

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Define/Use Testing Definitions

• A definition-use (sub)path with respect to a
  variable v (denoted du-path) is a (sub)path in
  PATHS(P) such that, for some , there
  are define and use nodes DEF(v,m) and USE(v,n)
  such that m and n are the initial and final nodes
  of the (sub)path
• A definition-clear (sub)path with respect to a
  variable v (denoted dc-path) is a definition-use
  (sub)path in PATHS(P) with initial and final
  nodes DEF(v,m) and USE(v,n) such that no other
  node in the (sub)path is a defining node of v
• DU-paths that are not definition-clear are
  potential trouble paths

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Agenda

• Define/Use Testing Definitions
• Define/Use Testing Example
• Commission Problem
• DU-Path Test Coverage Metrics

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Define/Use Testing Example

• Commission Problem
• Computes the commission on the sales of four
  salespersons based on the total number of locks,
  stocks and barrels sold by each one of them

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Define/Use Testing Example
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Define/Use Testing Example
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Define/Use Testing Example
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Define/Use Testing Example

• We use the defining and usage nodes in
  conjunction with the program graph to identify
  various definition-use and definition-clear paths
• Its a judgment call whether or not
  non-executable statements such as constant
  (CONST) and variable (VAR) declaration statements
  should be considered as defining nodes

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Define/Use Testing Example
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Define/Use Testing Example
DU-paths such as lt26,26gt are disallowed
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Agenda

• Define/Use Testing Definitions
• Define/Use Testing Example
• Commission Problem
• DU-Path Test Coverage Metrics

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DU-Path Test Coverage Metrics

• The set T satisfies the All-Defs criterion for
  the program P iff for every variable , T
  contains definition clear (sub)paths from every
  defining node of v to a use of v
• The set T satisfies the All-Uses criterion for
  the program P iff for every variable , T
  contains definition-clear (sub)paths from every
  defining node of v to every use of v, and to the
  successor node of each USE(v,n)
• The set T satisfies the All-P-Uses/Some C-Uses
  criterion for the program P iff for every
  variable , T contains definition-clear
  (sub)paths from every defining node of v to every
  predicate use of v, and if a definition of v has
  no P-uses, there is a definition-clear path to at
  least one computation use

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DU-Path Test Coverage Metrics

• The set T satisfies the All-C-Uses/Some P-Uses
  criterion for the program P iff for every
  variable , T contains definition-clear
  (sub)paths from every defining node of v to every
  computation use of v, and if a definition of v
  has no C-uses, there is a definition-clear path
  to at least one predicate use
• The set T satisfies the All-DU-paths criterion
  for the program P iff for every variable ,
  T contains definition-clear (sub)paths from every
  defining node of v to every use of v, and to the
  successor node of each USE(v,n), and that these
  paths are either single loop traversals, or they
  are cycle free

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DU-Path Test Coverage Metrics

• Example All-Uses criterion wrt locks
• All-C-Uses
• lt22,26gt, lt29,26gt
• All-P-Uses
• lt22,23gt, lt29,23gt
• All-Uses All-C-Uses Union All-P-Uses
• lt22,26gt, lt29,26gt, lt22,23gt, lt29,23gt

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DU-Path Test Coverage Metrics

• When one test coverage metric subsumes another, a
  set of test cases that attains coverage in terms
  of the first metric necessarily attains coverage
  with respect to the subsumed metric
• Since several du-paths are present in a full
  program execution path (traversed by a test
  case), the higher forms of coverage metrics dont
  always imply significantly higher numbers of test
  cases
• The missing du-paths (8, 9, 14, 18, 19) are all
  traversed by a test case in which nothing is sold
  (i.e., the first value of locks is -1)

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Agenda

• Define/Use Testing Definitions
• Define/Use Testing Example
• Commission Problem
• DU-Path Test Coverage Metrics

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References

• Software Testing A Craftsman's Approach 2nd
  edition, Paul C. Jorgensen, CRC Press (Chapter 10
  (10.1))