Domain Testing: Divide and Conquer - Testing Education

Appendix A: Equivalence Class Analysis Heuristics (continued)
Variable Equivalence
classes
x
Exclusive ranges (Open-ended):
Consider a variable ‘y’ which can take values only between the range v1 to v2, the end
points being exclusive.
Analysis:
Step 1: Represent this variable as a mathematical range expression.
v1 < y < v2
Test case
(Best
representatives)
Step 2: Identify the risks associated with this variable.
• Failure to process values between v1+1 and v2-1 correctly
• Mishandling of values below v1+1
• Mishandling of values above v2-1
Step 3: Determine the input domain for this variable
The input domain is the set of all possible values that can ever be inputted to the
variable ‘y’.
Step 4: Partition the input domain based on the identified risks.
The following is the corresponding equivalence class table for this example:
© Sowmya Padmanabhan, 2003
Risk Notes
v1 -- v2 v1, v2 1) Failure to process values between v1
and v2 correctly
2) Mishandling higher and lower
boundary values.
< v1 v1–1 1) Mishandling of values below v1
2) Mishandling of values just beneath the
lower boundary.
> v2 v2+1 1) Mishandling of values above v2
2) Mishandling of values just above the
upper boundary.
2