The Starfleet examination that qualifies an officer to command the bridge, which Deanna Troi passes only after ordering a simulated crewmate to his death.
The Bridge Officer's Test is the examination a Starfleet officer must pass to stand watch in command of a starship and to hold the rank of full commander. It covers a broad range of ship's operations and ends with a simulated engineering emergency run on the holodeck.
It is the secondary story of Thine Own Self. Inspired by a class reunion and by her time in command during the events of Disaster, Deanna Troi asks Riker to let her take the test. She passes the written sections but fails the simulation again and again, because every technical fix she tries ends with the ship destroyed.
A remark of Riker's about duty shows her the point. She orders the holographic Geordi La Forge into a lethal crawlway to make the repair, proving she can send a friend to die for the ship, and is promoted to commander.