What is the test for a motion under section 631.8 of the California Code of Civil Procedure?

Code of Civil Procedure section 631.8 provides in part: "(a) After a party has completed his presentation of evidence in a trial by the court, the other party, without waiving his right to offer evidence in support of his defense or in rebuttal in the event the motion is not granted, may move for a judgment. The court as trier of the facts shall weigh the evidence and may render a judgment in favor of the moving party . . . ." The purpose of Code of Civil Procedure section 631.8 is "to enable the court, when it finds at the completion of plaintiff's case that the evidence does not justify requiring the defense to produce evidence, to weigh evidence and make findings of fact. [Citation.]" (Pettus v. Cole (1996) 49 Cal.App.4th 402, 424.)