Domain Testing: Divide and Conquer - Testing Education

Appendix B: Guidelines for filling in “all-pairs combination”
table (continued)
7. The first row has the variable names (with the one with max test cases first and
the one with min test cases last). Each succeeding row (except blank rows) will
contain a combination that addresses “total (total-1)/2” pairs where ‘total’ = total
number of variables.
8. We begin filling the table by filling in the column corresponding to first variable
first. To do that, follow the following steps:
a. Repeat the first test case value of the first variable as many times as is the
value of Max 2 (number of test case values of second variable) in the first
column. Call this set 1.
b. Leave a blank row after the set in case you need to add extra test cases
later.
c. Similarly, repeat the second test case value of the first variable as many
times as is the value of Max 2 in the first column starting from the row
that is after the blank row succeeding the first set. Now you have set 2.
d. Do the above with the remaining test case values of first variable. Leave a
blank row after every set so that incase you need to add an extra test case
here, you wouldn’t have to shift the rows up and down. By doing the
above you will have filled in column corresponding to the first variable
completely. Now, we have as many sets as the value of Max 1 is. You just
now have to deal with the other variables. Please note that number of rows
keep increasing progressively as you add blank rows. Make sure you don’t
number the blank rows.
9. The heuristic of filling in test case values of second variable (values in cells
corresponding to second column) is to list the test case values of the second
variable one after the other starting from value 1 and ending at last value in the
column corresponding to second variable. By doing this for every set, you
eventually will fill the column corresponding to the second variable completely.
10. If there is a third variable then for the first set in the column corresponding to the
third variable, list the test cases in the order, that is, first test case followed by the
second, so on and so forth until you reach the last test case. If the number of test
cases of the third variable is less than the number of test cases of the second then
you will have at least one cell in the set that remains unfilled by the procedure
described above. In such an event, just repeat the sequence of the set again until
you have filled all cells in the set.
11. By now, you will have filled in all the cells belonging to set 1 of the third
variable. Now, start changing the order of the values for every successive set for
the third variable. One way to do this is to imagine that the values are connected
© Sowmya Padmanabhan, 2003
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