Part of the reason market research is important is to understand your prospective customers and to define and market your product accordingly. However, the testing of your product can also benefit from market research.
As I've expanded Dadnab to other areas (it is currently operational in Austin, Boston, Chicago, Dallas, Houston, Seattle, and the tri-state New York, New Jersey, and Connecticut area), I've used Google Maps extensively to come up with test cases. For each area, Dadnab has a suite of anywhere from 30 to 60 tests that I run periodically to ensure it is working properly.
Yet you don't improve what you don't measure. Occasionally, when I run into someone who lives in a covered area and ask them for locations to plug into Dadnab, Dadnab doesn't handle it well. So I now conduct on-going market research that polls prospective users for information about the trips they actually make. I then incorporate these trips into the suite of tests.