Software Testing and Quality Assurance

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Software Testing and Quality Assurance

• Lecture 6 - Software Testing Techniques

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Lecture Outline

• Introduction to domain testing.
• How to select test cases based on domain
  boundaries.

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Domain Testing

• Partition input of a program using the program
  structure itself.
• Input space is first partitioned into a set of
  mutually exclusive classes.
• Each corresponds to a program path.
• Test cases are selected from
• The domain boundaries
• Points close to the domain boundaries.

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Example

• int f (float x, y)
• float w, z
• w x y
• if (x y 2)
• z x - 3y
• else
• z 2x - 5y
• if (z w gt 3)
• z f(x,y,z)
• else
• z g(x,y,z)
• Return z

Two If/then/else statements
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Example

• int f (float x, y)
• float w, z
• w x y
• if (x y 2)
• z x - 3y
• else
• z 2x - 5y
• if (z w gt 3)
• z f(x,y,z)
• else
• z g(x,y,z)
• Return z

C1a xy2
C1b xylt2
C2a(C1 T) 2x-2ygt3
C2b(C1 F) 3x-4ygt3
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Domains for the program
(2,0)
TT
FF
(3/22,0)
(0,2)
FT
(1,0)
TF
(0,3/22)
(0,4/3)
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Simple Compound Predicates

• Simple predicates contain a set of variables such
  as
• lt, gt, etc.
• Create simple boundaries.
• Compound predicate are
• AND operators
• OR operators
• Combination of both

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Compound Predicate -Example
X 0 V X 2
X 0
X 2
Function 1
Function 2
Sun-domain
Sun-domain
This region is not part of the sub-domain being
tested.
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Loops in programs

• If each program path corresponds to a function
  then for loops
• We may have an infinite number of paths.
• An infinite number of equivalence classes.
• Apply zero- to-many rule.
• Minimum number of times a loop can execute is
  zero.
• Some loops have upper bound, so treat that as a
  path.

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Loops in programs

• Zero times - we can test paths that do no execute
  the loop.
• Once - test that the loop can be entered and
  result of single iteration are correct.
• Twice - to test that the results remain correct
  between different iterations of loop.
• N times (more than 2) - to test that an arbitrary
  number of iterations returns the correct results
  and
• N 1 times - test that after an arbitrary number
  of iterations the result remain correct.

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Key points

• To select test cases, input space is first
  partitioned into a set of equivalence classes.
• Simple predicates.
• Compound predicates.
• Loops