She's a police officer. She has killed a man during a mission. Standard departmental procedure meant that she would spend the morning in Testing. Any officer whose discharge of weapon resulted in termination of life was required to undergo emotional and psychiatric clearance before resuming duty.
It sounds like she's a beat cop (she patrols the streets, possibly on foot).
When she is in "Testing," she will be off the streets (not patrolling the streets).
She doesn't intend to be away from her street patrol for more than twenty-four hours.