Predicates, Path Predicates and Achievable Paths
Predicate:
The logical function evaluated at a decision is called predicate
The direction taken at a decision depends on the value of decision variable
Some examples are: A>0, x + y >= 90...........
Path Predicate:
A predicate associated with a path is called path predicate
Example: "X is greater than zero" is true
AND
"X + Y >=90" is false
AND
"W is either negative or equal to 10" is true
Multiway Branches:
The path taken through a multiway branch such as computed GOTO, case statement, or jump tables cannot be directly expressed in TRUE/FALSE terms.
Although, it is possible to describe such alternatives by using multi valued logic, a practical approach is to express multiway branches as an equivalent set of if... then...else statements
For example, a three way case statement can be written as:
if case = 1 DO A1
ELSE (IF Case = 2 DO A2 else DO A3 END IF)END IF
Inputs:
In testing, the word input is not restricted to direct inputs, such as variables in a subroutine call, but includes all data objects referenced by the routine whose values are fixed prior to entering it
For example, inputs in a calling sequence, objects in a data structure, values left in registers or any combination of object types
The input for a particular test is mapped as a one dimensional array, called as an Input Vector
The logical function evaluated at a decision is called predicate
The direction taken at a decision depends on the value of decision variable
Some examples are: A>0, x + y >= 90...........
Path Predicate:
A predicate associated with a path is called path predicate
Example: "X is greater than zero" is true
AND
"X + Y >=90" is false
AND
"W is either negative or equal to 10" is true
Multiway Branches:
The path taken through a multiway branch such as computed GOTO, case statement, or jump tables cannot be directly expressed in TRUE/FALSE terms.
Although, it is possible to describe such alternatives by using multi valued logic, a practical approach is to express multiway branches as an equivalent set of if... then...else statements
For example, a three way case statement can be written as:
if case = 1 DO A1
ELSE (IF Case = 2 DO A2 else DO A3 END IF)END IF
Inputs:
In testing, the word input is not restricted to direct inputs, such as variables in a subroutine call, but includes all data objects referenced by the routine whose values are fixed prior to entering it
For example, inputs in a calling sequence, objects in a data structure, values left in registers or any combination of object types
The input for a particular test is mapped as a one dimensional array, called as an Input Vector
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