Cal. Prob. Code § 1000

Except to the extent that this code provides applicable rules, the rules of practice applicable to civil actions, including discovery proceedings and proceedings under Title 3a (commencing with Section 391) of Part 2 of the Code of Civil Procedure, apply to, and constitute the rules of practice in, proceedings under this code. All issues of fact joined in probate proceedings shall be tried in conformity with the rules of practice in civil actions.