How can you possibly test modern software fully?

Pairing up for fun and profit

Notice, from Figure 17, that 10 test runs cover all the Database/Client Type and Operating System/Client Type pairs:

If there are more variables, continue the same procedure of creating pairs with the values from the last variable and the values for the other variables.

In our examples, the Browser values are only valid when the Client Type is Web. The following table (Figure 18) shows the Browser values added to the Web test runs:

Verify that all the Web pairs are present for the other variable values. There is a pair for each Browser value and the Web Client Type (Figure 19):

As you can see in Figure 20, there's a pair for each Operating System and Browser value:

Finally, check the pairs for the Browser values and the Database values. Notice, from Figure 21, that the Oracle/Internet Explorer and Access/Firefox pairs are missing:

You could simply add two new test runs to cover the missing Database and Browser combinations, however, before you do that, check for duplicate pairs to see if you can incorporate the missing pairs into the existing runs. Notice, from Figure 22, that the Solaris/GUI and the Windows/GUI pairs are duplicated in the Access and Oracle groups.

You can change the Solaris/GUI pair in the Oracle group and add the Internet Explorer/Oracle pair to that run without affecting the other pairs. You can also change the Windows/GUI pair in the Access group and add the Firefox/Access pair to that run, giving us Figure 23: