Schaum's Outline Series

154
10.3.4.6 C1 Subsumes C0
EXAMPLE 10.8—C1 Subsumes C0
For the triangle problem, in Example 10.3 we selected good test cases until we
achieved the C0 coverage. The test cases were (3,4,5—scalene), (3,5,3—
isosceles), (0,1,0—bad inputs), and (4,4,4—equilateral). These tests also covered
four out the five possible outputs. However, we can achieve C1 coverage with two
test cases: (3,4,5—scalene) and (0,0,0—bad inputs). This test is probablynot as
good as the first test set. However, it achieves C1 coverage and it also achieves
C0 coverage.
10.4 Data Flow Testing
CHAPTER 10 Software Testing
Data flow testing is testing based on the flow of data through a program.
Data flows from where it is defined to where it is used. A definition of data,
or def, is when a value is assigned to a variable. Two different kinds of use
have been identified. The computation use, or c-use, is when the variable
appears on the right-hand side of an assignment statement. Ac-use is said
to occur on the assignment statement. The predicate use, or p-use, is when
the variable is used in the condition of a decision statement. Ap-use is
assigned to both branches out of the decision statement. A definition free
path, or def-free, is a path from a definition of a variable to a use of that
variable that does not include another definition of the variable.
EXAMPLE 10.9—Control Flow Graph of Triangle Problem (Example 10.3)
The control flow graph in Fig. 10-2 is annotated with the definitions and uses of the
variables a,b, and c.
p-use a,b,c
p-use a,b,c
p-use a,b,c
p-use a,b,c
abc
e
g
i
k
def a,b,c type
c-use type
p-use a,b,c
p-use a,b,c
p-use a,b,c
p-use a,b,c
d
f
h
j
def type
def type
def type
def type
Fig 10-2. Control flow graph of triangle problem.