1. Systems V & V, Quality and Standards
Dr Sita Ramakrishnan
School CSSE
Monash University

2. Test Coverage Criteria based on Data Flow Mechanisms
Topics
Program Structure
Categories of Data Flow Coverage Criteria
Data Flow Testing
References:
Peters J F and Pedrycz W,Software Engineering, An Engineering Approach, McGraW Hill, 2000, (Ch.12, Software Testing, pp )
Horgan J.R., London S., Lyu M.R. Achieving software quality with testing coverage measures. IEEE Computer, Sep. 1994: 60-69
Other references (books included in the slides, conference & journal papers) given in the handout for the unit
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3. Program Structure Program consists of blocks
Block consists of a sequence of statements
When a first statement is executed, the following statements are executed in the given order
Can be represented by a flow graph
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4. Testing Coverage Have looked at testing techniques such as:
Black-box testing which includes categories such as:
Syntax-driven driven testing – where specification is described by a certain grammar. -> Generate test cases such that each production rule is applied/tested at least once
Decision-table based testing – may suit if requirements have been written as if-then rules
Cause-effect graphs in functional testing – addresses limitations of decision table where all inputs are treated separately although real world problem demand another approach. Boundary-value analysis & equivalence class partition also assume the independence of input
Structural testing – includes basic categories such as statement, branch & path coverage tests
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5. Testing Coverage More on Black-box Testing with Cause-Effect Graphs:
Cause-effect graphs capture relationships between specific combination of inputs (causes) and outputs (effects).
Helps avoid combinatorial explosion associated with decision table approach
Causes and Effects represented as nodes of a
cause-effect graph – includes intermediate
nodes to link cause & effects in forming logical
expressions
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6. Testing Coverage – Cause-Effect Graphs
Eg. of an ATM transaction system. Causes and Effected listed as:
Causes: C1 : Command is credit, C2: Command is Debit
C3: Account No. is valid, C4: Trans. Amount is valid
Effects: E1: Print “invalid command”, E2: “invalid acct no”
E3: “debit no. not valid”, E4 & E5: debit & credit a/c respectively or C1 E1
and C2 E2
and C3 E3
and C4
and E4
Cause-effect graph
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7. Testing Coverage – Cause-Effect Graphs
4 input (Cause) nodes & 5 output (Effect) nodes
the node in between input (C ) & output (E ) realise “and” or “or” operators
Processing node used in cause-effect graph – and, or, negation, and with processing node,
“and” - effect occurs if all inputs are true
“or” - effect occurs if at least one input is true
“negation” – effect occurs if inputs are false
Cause-Effect graph helps determine the corresponding test cases
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8. Testing Coverage – Cause-Effect Graphs
Eg. To determine test cases from C-E Graph
Want to find out the causes for E3 say given: C2 C3 C4
C1 C2 C3 C4 X
X= (don’t care condition)
1 = true, 0 = false
E3 does not depend on Cause (C1)
and E3
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9. Test coverage based on Data Flow Coverage Criteria
Why data flow orientation in testing?
Data structures and their usage are essential elements of any code and hence need to be taken into account when looking at software testing
Main categories of data flow coverage criteria
basic block
all-use
c-use
d-use
du-path
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10. Test coverage based on Data Flow Coverage Criteria
In a piece of Java code: Eg
sum = 0; Definitions shown in blue
prod = 0;
i = 1;
while (i <= n)
{ sum+ = i; basic block shown in purple
prod* = i; > prod* = i an eg of “use”
i > i++ also an eg of “use”
} if “use” appears in a computational
if (k == 0) print_results1; expression, the pair is c-use,
if in predicate, resulting pair is p-use
if (k == 1) compute;
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11. Test coverage based on Data Flow Coverage Criteria
Definition – value stored in a memory location
Defined (d) – data structure is defined, created or initialized
when it is given a valid state
Use – value fetched from a memory location
C-use – used in computation or output statement &
- associated with each node
P-use – used in a predicate& associated with each edge
C-uses
Decision
Basic Block
All-uses
P-uses
Hierarchy of different dataflow
coverage criteria
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12. Test coverage based on Data Flow Coverage Criteria
Def-use Graph
Obtained from the flow graph
Associate with each node the sets
C-use (i) - variables which have global c-uses in block i
Def (i) - variables with global definitions in block i
Associate with each edge (i,j)
P-use (i,j) – variables which have p-uses on edge (i,j)
Define sets of nodes
dpu(x,i) - edges (j,k) such that x Є p-use(j,k) and there is a def-clear path w.r.t. x from i to (j,k)
dcu(x,i) - nodes j such that x Є c-use(j) and there is a def-clear path w.r.t. x from i to j
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13. Test coverage based on Data Flow Coverage Criteria
Def-use Graph Paths – Definitions
Complete path – path from entry node to exit node
Def-clear path w.r.t. x from node i to node j and
from node i to edge nm , j
a path (i, n1,n2, …n , j) containing no definitions or undefinitions of x in nodes n1, n2, ….n m m
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14. Test coverage based on Data Flow Coverage Criteria
The family of data flow testing criteria is based on requiring that –
The test data execute definition-clear paths from each node containing a global definition of a variable to specified nodes containing global c-uses and edge containing p-uses of that variable
For each variable definition, data flow testing criteria require that
All/some definition-clear paths w.r.t. that variable from the node containing the definition to all/some of that uses/c-uses/p-uses reachable by some such paths be executed
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15. Test coverage based on Data Flow Coverage Criteria
All-def criterion
If variable x has a global definition in node i, the all-defs
criterion requires the test data to exercise some path which goes from i to some node or edge at which the value assigned to x in node i is used
All-uses criterion
If variable x has a global definition in node i, the all-uses
criterion requires the test data to exercise at least one path which goes from i to each node or edge at which the value assigned to x in node i is used
© S Ramakrishnan

16. Test coverage based on Data Flow Coverage Criteria
All-DU-paths criterion
If variable x has a global definition in node i, the all-DU-paths criterion requires the test data to exercise all paths which go from i to each node and edge at which the value assigned to x in node i is used
Other DF testing criteria
All-p-uses
All-c-uses
All-p-uses/some-c-uses
All-c-uses/some-p-uses
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17. Test coverage based on Data Flow Coverage Criteria
Hierarchy of data flow coverage criteria
all-paths
all-du-paths
all-uses
all-c-uses-some-p-uses all-p-uses-some-c-uses
all-c-uses all-defs all-p-uses
all-edges
all-nodes
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18. Test coverage based on Data Flow Coverage Criteria
Interprocedural Data Flow Testing
Most df testing methods deal with dependencies
that exist within a procedure – intra procedural aspect
Data dependencies may also exist between procedures
Requires analysis of flow of data across these procedure/module boundaries
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19. Test coverage based on Data Flow Coverage Criteria
Homework: Closer look at Table 12.6 Coverage Criteria on P.479 in Peters & Pedrycz text (see slide 1 for Reference details)
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