On the trial of the peremptory exception pleaded at or prior to the trial of the case, evidence may be introduced to support or controvert any of the objections pleaded, when the grounds thereof do not appear from the petition.
When the peremptory exception is pleaded in the trial court after the trial of the case, but prior to a submission for a decision, the plaintiff may introduce evidence in opposition thereto, but the defendant may introduce no evidence except to rebut that offered by plaintiff.
No evidence may be introduced at any time to support or controvert the objection that the petition fails to state a cause of action.