Unit 3 Control Flow Testing contains Concept of CFT, Generate Test Input Data, Activities of Generating Test Input Data, Control Flow Graph, Path Selection Criteria, Techniques for Path Selection statement wise, branch wise, predicate wise etc. and Generating Test Input.

1. CONTROL FLOW TESTING
UNIT - 3
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Prepared By: Ravi J Khimani, CSE Department, SLTIET, Rajkot

2. CONCEPTS
 Two kinds of Basic Statements in Program
 Assignment Statements
 Conditional Statements
 Conditional Statements alters the default
sequential control flow of program.
 A program unit must be having a proper entry-point
and exit-point, single or multiple.
 Sequence of instruction from Entry-Point to Exit-
Point is called Path. 2

3. CONCEPTS
 A specific input value causes a specific path to be
executed.
 That performs desired operations to produce
expected output.
 More execution of higher number of paths, at
higher cost, may not be effective to relieve defaults.
 Control Flow Testing is a kind of Structural Testing
which is performed by programmer to test code
written by them.
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4. GENERATE TEST INPUT DATA FOR CFT
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5. ACTIVITIES IN GENERATE TEST INPUT DATA
 Over all idea of generation test input data is to
perform control flow testing.
 Those activities performed and intermediate results
are produced.
 Input: Source Code & Set of Path Selection Criteria.
 Generation of a Control Flow Graph:
 aim to visualize all possible paths in program unit.
 Graphical Representation of execution.
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6. ACTIVITIES IN GENERATE TEST INPUT DATA
 Selection of Paths:
 Paths are selected from CFG to satisfy Path Selection Criteria.
 Generation of a Test Input Data:
 A Path can be executed if and only if input to program unit
cause all conditional statements to true or false as per CFG.
 Such path is called Feasible Path.
 Otherwise it’s known as Infeasible Path.
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7. ACTIVITIES IN GENERATE TEST INPUT DATA
 Feasibility Test of Path:
 Idea behind it to check the path is to meet the path selection
criteria.
 If some path founds to be infeasible, then new paths are
selected to be feasible.
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8. CONTROL FLOW GRAPH
 A CFG is graphical representation of a program.
 Three symbols are used.
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9. 9

10. PATH REPRESENTATION
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11. PATH SELECTION CRITERIA
 A Program Unit with small number of paths,
executing all paths may desirable and achievable.
 But if large number of paths, then executing all
path may not be practical.
 What paths do I select for testing?
 it is more productive for programmers to select a
small number of program paths in an effort to
reveal defects
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12. ADVANTAGES OF PATH SELECTION
 Following, advantages of selecting paths based on
defined criteria:
 The programmer needs to observe the outcome of
executing each program construct.
 do not generate test inputs which execute the same
path repeatedly. It’s a waste of resources.
 If same path updates state of program, then repeat
execution of same path is not identical.
 Programmer can know the program features that have
been tested and those not tested
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13. TECHNIQUES FOR PATH SELECTION
 All-Path coverage criteria
 If all-path are selected in CFG, then one can detect all
faults.
 Except those due to missing path error.
 Program may contain infinite number of paths.
 So, if all paths are selected to perform testing, then all-
path selection criteria has been satisfied.
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14. FOR EXAMPLE - ALL-PATH COVERAGE CRITERIA
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15. CFG
FOR
OPENFILES()
FUNCTION
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16. INPUT DOMAIN AND PATHS
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17. TECHNIQUES FOR PATH SELECTION [CONT…]
 Statement Coverage Criteria
 Refers to the individual program statement and
measure the outcome.
 100% achieved if all statements are executed.
 Its weakest coverage criteria.
 All program statements must be represent in CFG with
proper representation.
 So, basic problem is to select few feasible path for
covering all nodes in CFG.
 So, path length should be longer in increasingly
manner.
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18. TECHNIQUES FOR PATH SELECTION [CONT…]
 Branch Coverage Criteria
 Each node in CFG may have one or two branches.
 Covering branch means selecting path that includes
that branch.
 Complete branch coverage means selecting a number
of paths such a way that all possible branches must be
included in those path.
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19. TECHNIQUES FOR PATH SELECTION [CONT…]
 Predicate Coverage
Criteria
 Includes logic check
inside program, that
covers all
statements and
branch coverage
criteria.
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20. TECHNIQUES FOR PATH SELECTION [CONT…]
 So need to design test cases that covers all the
possible conditions (logic).
 The False branch of node 5 (Figure 4.9a) is
executed under exactly one condition, namely,
when OB1 = False, OB2 = False, and OB3 = False,
whereas the true branch executes under seven 20

21. TECHNIQUES FOR PATH SELECTION [CONT…]
 If all possible combinations of truth values of the
conditions affecting a selected path have been
explored under some tests, then we say that
predicate coverage has been achieved.
 For Example, The path taking the true branch of
node 5 in Figure 4.9a must be executed for all
seven possible combinations of truth values of
OB1, OB2, and OB3 which result in OB = True.
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22. GENERATING TEST INPUT
 After having an identified path, main question is
how to select input values?
 Such that, when program is executed with such
input values, the selected path gets executed.
 So, it needs to identify input to force path
execution.
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23. GENERATING TEST INPUT
 For that some terms need to go through,
 1. Input Vector
 Collection of all data entities
 Fixed prior entering to routine / program.
 Like, input arguments, global variables, files, network
connections, timers, etc…
 For example, input vector for OPENFILE() function is
presence or absence of file1, file2, file3 and so on.
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24. GENERATING TEST INPUT
 2. Predicate
 It’s a logical function evaluated at decision point.
 In this figure, OB is a predicate at decision point
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25. GENERATING TEST INPUT
 3. Path Predicate
 It’s a set of predicates associated with the path.
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26. GENERATING TEST INPUT
 4. Predicate Interpretation
 Predicate interpretation is defined as the process of
symbolically substituting operations along a path in
order to express the predicates solely in terms of the
input vector and a constant vector.
 Means, there is no role play of local variables inside
functions because they are not visible to outside
functions.
 Those local variables can be easily substituted by the
elements of input vector using symbolic substitution.
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27. GENERATING TEST INPUT
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28. GENERATING TEST INPUT
 5. Path Predicate Expression
 An interpreted path predicate is called a path predicate
expression with following properties.
 composed of input vector and constant vector
 set of constraints composed from input vector
 Forcing input values can be generated from constraints in path
predicate expression.
 If set of constraint can not be solved, then selected path can
not be executed.
 An infeasible path is not responsible for path predicate
expression, that dissatisfied.
 infeasibility of path forces to choose other path which meet
proper criteria. 28

29. GENERATING TEST INPUT
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30. GENERATING TEST INPUT
 6. Generating Input Data from PPE
 The respective Path Predicate Expression must be
solved in order to generate input data which can force a
program to execute a selected path.
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31. COINCIDENTAL CORRECTNESS
 In spite of the fault available in the code, some test
data produces the correct result, that’s known as
Coincidental Correctness.
 For Example,
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Produces correct result in
CFG at slide number 9

32. CONTAIN INFEASIBLE PATH
 A CFG may contain number of paths, shorter or
longer.
 Not practical to execute or analyze all paths.
 So, define strategy like,
 Select as many as sort paths which are feasible
 Choose longer path to achieve coverage of statements,
predicates and branches.
 Reduce number of infeasible paths through language
design, program design, program transformations.

33. CONTAIN INFEASIBLE PATH
 Bertoline and Marre,
 gave an algorithm which generate set of feasible paths.
 Based on idea, Reduced Flow Graph, called ddgraph.
 Yates & Malevries,
 Suggests a strategy to select a path with minimum
number of predicates.