Domain Testing: Divide and Conquer - Testing Education

According to Ostrand and Balcer (1988), the cause-effect graphing
technique can get very complicated and very difficult to implement, especially
when the number of causes is too large.
2.03.02 Pairwise / Orthogonal Arrays Testing
One of the solutions to combinatorial explosion is pairwise testing. “Pairwise
testing (or 2-way testing) is a specification based testing criterion, which requires
that for each pair of input parameters of a system, every combination of valid
values of these two parameters be covered by at least one test case” (Lei & Tai,
1988, p. 1).
Bolton (2004) defined an orthogonal array (OA) as: “An orthogonal array
has specific properties. First, an OA is a rectangular array or table of values,
presented in rows and columns, like a database or spreadsheet. In this spreadsheet,
each column represents a variable or parameter” (About Orthogonal Arrays
section, 2).
The value of each variable is chosen from a set known as an alphabet. This
alphabet doesn't have to be composed of letters—it's more abstract than
that; consider the alphabet to be "available choices" or "possible values". A
specific value, represented by a symbol within an alphabet is formally
called a level. That said, we often use letters to represent those levels; we
can use numbers, words, or any other symbol. As an example, think of
levels in terms of a variable that has Low, Medium, and High settings.
Represent those settings in our table using the letters A, B, and C. This
gives us a three-letter, or three-level alphabet.
At an intersection of each row and column, we have a cell. Each cell
contains a variable set to a certain level. Thus in our table, each row
represents a possible combination of variables and values… (About
Orthogonal Arrays section, 3-4)
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