A character with the Berserk edge
...immediately after suffering a wound (including a Shaken result from physical damage), (...) must make a Smarts roll or go Berserk.
Going Berserk has pros and cons, and in some situations the player may think it is in the benefit of the character to go Berserk (for example, if they received three wounds they could not soak and they want to avoid the -3 penalty to all trait rolls).
Can the player decide not to do the roll in order to make sure the character goes Berserk? The text from the rules seems to suggest that you can.