Software Testing Methodologies Dichotomies

Strategies in Data Flow Testing

Data Flow testing strategies are structural strategies

In contrast to the path testing strategies, data flow strategies take in to account, what happens to data objects on the links in addition to the raw connectivity of the graph

In other words, data flow strategies requires data flow link weights (d,k, du, dk)

A strategy X is stronger  than another strategy Y, if all test cases produced under Y are included in those produced under X - conversely for  weaker

Terminology

Clear Path Segment:

Clear Path Segment with respect to variable X, is a connected sequence of links such that X is (possibly defined on the first link and not redefined or killed on any subsequent link of that path segment

All paths in image (a) are definition clear because variables X and Y are defined only on the first link (1, 3) and not thereafter

Image (b)shows more complicated situation. The following path segments are definition-clear:

(1, 3, 4), (1, 3, 5), (5, 6, 7, 4), (7, 8, 9, 6, 7), (7, 8, 9, 10),(7, 8,10) (7, 8, 10, 11)

Sub graph (1, 3, 4, 5) is not definition-clear because the variable is defined on (1, 3) and again on (4, 5)

For practice, try finding all the definition-clear subparts for this routine (i.e. for all variables)

Loop-Free Path Segment:

It is a path segment for which every node in it is visited at most once

Example: Path (45678, 10) in image (b) is loop free, but path (10, 11, 4, 5, 6, 7, 8, 10, 11, and 12) is not because nodes 10 and 11 are each visited twice

Simple Path Segment:

It is a path segment in which at most one node is visited twice

Example:  In image (b), (7, 4, 5, 6 and 7) is a simple path segment. a simple path segment is either loop-free or if there is a loop, only one node is involved

A du Path:

From node i to k is a path segment such that if the last link has a computational use of X, then the path is simple and definition-clear; if the penultimate (last but one) node is j- that is, the path is (i, p, q,..... r, s, t, j and k) and link (j, k) has a predicate use-then the path form i to j is both loop-free and definition-clear