SIM5102SOFTWARE EVALUATION

Measuring Internal Product Attributes :Flowgraph measurement(structure)

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Objectives Be able to measure internal product attributes

based on flowgraph

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Overview from last lecture McCabe's metric based on flowgraph Draw flowgraphs

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Flowgraph : Basic Control Structure

Sequence : eg a list of instructions with no other control structure involved

Selection : eg if ...then... else Iteration : eg do...while, repeat...until

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Flowgraph : terminologies In-degree : number of arcs arrive at the node Out-degree : number of arcs leaves the node Procedure nodes : nodes with out-degree 1 Predicate nodes : nodes with out-degree other than 1 (except

stop node) Stop node : node with out-degree 0 Path : sequence of consecutive edges, may be traversed more

than once Simple path : traversing without repeating the edges

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Basic flowgraph structures Sequence : Pn or Pn(X1,X2,...,Xn) or X1;X2;...Xn

Selection

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x1 x2 x3 x4

t f

A

x

D0 or D0(A,X)if A then X

A

t f

X Y

D1 or D1(A,X,Y)if A then X else Y

Basic flowgraph structure (cont..)

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A

...........

a1

a2an

X1 Xn

Cn or Cn(A, X1,X2,...,Xn)

Case A ofa1 : X1a2 : X2..an : Xn

Basic flowgraph structure Iteration

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A

f t

D2 or D2(A,X)while A do X

X

X

At

f

D3 or D3(A,X)repeat X until A

Sequencing operation Let F1 and F2 be two flowgraphs. The sequence of F1 and F2 is the flowgraph

formed by merging the stop node of F1 with the start node of F2

The resulting flowgraph can be written as

F1;F2

Seq(F1,F2)

P2(F1,F2)9

Sequencing (cont...) Merging two flowgraphs

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D1

D3

sequence

D1;D3

Nesting operation Let F1 and F2 be two flowgraphs. Suppose F1

has a procedure node X The nesting of F2 on to F1 at X is the

flowgraph formed from F1 by replacing the arc from X with the whole of F2

The resulting flowgraph can be written as

F1(F2 on X)

F1(F2)

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Nesting (cont...)

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D1

D3

Xwith

Nestedon X

D1(D3)

Prime flowgraph Flowgraphs that cannot be decomposed non-

trivially by sequencing or nesting Examples

Pn

D0, D1, D2 and D3

Cn

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S-structured Graph A family (S) of prime flowgraph is called S-

structured Graph (or S-graphs) if it satisfies the following recursive rules:

1. Each member of S is S-structure

2. if F and G are S-structured flowgraphs, so is the sequences F;G and nesting of F(G)

3. No flowgraph is S-structured unless it can be generated by finite number of application of the above (step 2) rules

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Prime decomposition Any flowgraph can be uniquely decomposed

into a hierarchy of sequencing and nesting primes

Decomposition tree – can be determined from a given graph

It describes how the flowgraph is built by sequencing and nesting

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Hierarchical Measures

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Assume that S in an arbitrary set of primes. We say a measure m is ahierarchical measure if it can be defined on the set of S-graphs by specifying

- m(F) for each F is a member of S (we call this as M1)

- the sequencing function(s) (e call this as M2)

- the nesting functions hF for each F is a member of S (we call this as M3)

Depth of Nesting Depth of nesting, a, for a flowgraph F can be

expressed in terms of:

- primes: a(P1) = 0, and if F is a prime is not equal to P1, then a(F) = 1

- sequence : a(F1;...;Fn) = max(a(F1),..,a(Fn))

- nesting : a(F(F1,...,Fn))

= 1 + max(a(F1),..,a(Fn))

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Example F = D1((D0;P1;D2),D0(D3))

a(F) = 1 + max(a(D0;P1;D3),a(D0(D3)))

= 1 + max(max(a(D0),a(P1),a(D3)), 1 + a(D3))

= 1 + max(max(1,0,1), 1 + 1)

= 1 + max(1,2)

= 3

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Test Coverage Measures Statement coverage

- a set of paths that every node lies on at least one path

Branch coverage

- a set of paths such that every edge lies on at least one path

All Path coverage

- exercising every single path

- infinite number if there any loop19

Test Coverage Measures Simple path coverage

- every path which does not contain the same edge more than once

Visit-each-loop

- branch coverage is satisfied

- for every loop, there are paths for each control flows both straight pass the loop and around the loop at least once

Linearly independent paths

- the execution of set of linearly independent paths

- an independent path must move along at least one edge that has not been traversed before the path is defined

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Minimum Number of test cases Have to know the minimum number of test cases in

order to

- plan the testing

- generating data

- how long testing will take Minimum number of path m(F) can be computed from

the decomposition tree

- strategy of testing

- value for the primes, sequencing, and nesting

- appendix 8.10.4

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Example : statement coverageF = D1((D0;P1;D2),D0(D3)) please refer to app. 8.10.4

m(F) = m(D1(D0;P1;D2),D0(D3))

= m(D0;P1;D2) + m(D0(D3))

= max(m(D0),m(P1),m(D2)) + m(D3)

= max(1,1,1) + 1

= 2

required paths : <2 10 12 14> <1 3 5 6 7 8 9>

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Class exercisebegin

Read input list

if the list is empty then

output “list empty

else

begin

sum := 0;

repeat

read next list entry A;

sum := sum + A;

until end of list

output sum;

end;

end.

1. draw the flowgraph2. draw the decomposition tree3. write the expression for the decomposition tree4. calculate the depth of nesting using hierarchical measure5. compute the minimum number of test cases for statement coverage.

Software Architecture

Morphology

Morphology - example

Tree Impurity

Tree Impurity

Internal Reuse

Modules and Components

Software Architecture

Cohesion

Cohesion

Coupling

Coupling

Coupling : Representation

Information Flow Measures

Information Flow Measures

Information Flow Measures

Information Flow Measures