Thanks, Davide!
I can see how that would work.
Another way I figured out to accomplish my goal was to set the limits for x with:
Context()->variables->set(x=>{limits=>[$bound, 10]});
Then I added test points to the function holding the problem answer from the negative part of the domain with:
$afunc->{test_at} = [-$bound, -$bound*2, -$bound*10];
This seemed to work well for my goal of checking an antiderivative with arcsec (|u|/a) in it.
The variable $bound was determined from the random variables in u and a.
Paul