Do we need to be on the lookout for applicants who are merely testing our practices?

Q: When interviewing a candidate for a job, I became suspicious that the job-seeker was a tester. Her answers to my questions seemed as though she was fishing for a slip-up. Does the EEOC send out testers to see whether employers are conducting their hiring processes within the law? What about civil rights groups? – C.B., District of Columbia