The Trial of the Flesh

The Trial of the Flesh was the most trying test given at the Temple. Involving the apprentice overcoming great physical pain, hardship, or loss, the test sometimes resulted in death or dismemberment. Throughout history, the Trial was known to involve bloodshed of some form. At the height of the Pius Dea Era, the Order subjected its apprentices to burst of energy applied directly to the skin, known as The Burning. While this type of torture was abandoned by the Order, battle scars were accepted as passage during the New Sith Wars. 
It wasn't that uncommon for Padawans who defeated a Lord of the Sith on the battlefield to pass the Trials of the Flesh, Skill, and Courage at the same time. During the Arkanian Revolution, Squire Kinning lost an arm in order to pass the tests. During the Golden Age, the Council saw the separation of Master and Padawan at the end of their journey together as a significant trial, as the relationship was usually very close.
During the Clone Wars, Padawan Anakin Skywalker lost his right forearm during a duel with Count Dooku on Geonosis. While this was out of recklessness, Master Kenobi convinced the Council to accept this as the Trial of the Flesh. During the Dark Times, Sith assassin Starkiller faced and defeated the simulacrum representation of his father in the High Council Chambers of the Coruscant Temple. In the reformed Order during the New Republic era, Apprentice Tenel Ka was able to overcome the loss of her left arm and refused to have a mechanical replacement, thus passing her test.
During the Galactic Civil War, Luke Skywalker passed the Trial of the Flesh by losing his right hand in his battle with his father, Darth Vader, in Cloud City.

The Trial of the Flesh is a test of a Jedi Padawan's ability to handle loss, hardship, and/or great pain.
To pass this test, a Jedi is tested in the testing chamber. 
If the Padawan obtained a scar, experienced dismemberment, or another form of trauma, the Padawan is not required to take this test.