It wouldn't make a lot of sense for an application exam to test the applicant's knowledge of police skills. Most applicants don't have any familiarity with the penal code or with police tactics and procedures.
Most entry tests assess problem solving ability, common sense, and general knowledge. Practice tests can give you an idea of what sort of questions may be on the actual exam, but I don't think anyone lacking in common sense or problem solving ability is going to learn either of those things through a set of Cliff notes.
Cogito ergo summopere periculosus.
Fiat justitia, ruat coelum.