Domain Testing: Divide and Conquer - Testing Education

that lead to the corresponding output. After they had done this for each output, they
used their brute-force algorithm to form a minimal set of combinations of inputs
that best represent each of the outputs. The two researchers considered their method
better than pairwise or orthogonal testing.
2.03.04 All Pairs Combination
Yet another solution to combinatorial explosion is all pairs combination. This is an
extension of pairwise testing, but it yields more combinations. According to Kaner
et al. (2002), “Every value of every variable is paired with every value of every
other variable in at least one test case” (p. 54). If there are n number of variables in
a program, then combinations generated due to the all pairs combination technique
will contain n*(n-1)/2 pairs in each combination (Kaner et al., 1999).
Cohen, Dalal, Parelius and Patton (1996) considered the all pairs approach
to be far better than the orthogonal arrays approach. They noted that in the pairwise
version of orthogonal testing, every pair of values must occur an equal number of
times, which makes this combinatorial approach very difficult to implement in
practice. They gave an example to prove their point. “For example, for 100
parameters with two values each, the orthogonal array requires at least 101 tests,
while 10 test cases are sufficient to cover all pairs” (p. 87). However, this technique
is only applicable to independent variables (Kaner & Bach, 2004, part 19).
2.03.05 Weak Robust Equivalence -Class Testing
Jorgensen (2002) cited four forms of equivalence class testing involving multiple
variables:
• Weak Normal Equivalence Class Testing: It is called normal because only
those test cases that contain valid values for each variable in the input
combination will be considered. It is called weak because not all possible
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