What is the test for establishing a proper venue for a tort action?

Real parties, however, contend that 'in the absence of an affirmative showing to the countrary, the presumption is' that the county in which the action is brought is the proper county (Smith v. Stanford Research Institute, 212 Cal.App.2d 750, 753, 28 Cal.Rptr. 481, and cases there cited). They seek to expand this rule to require negation of contract venue, even when the complaint clearly states a cause of action in tort alone. But to wrench such an excerpt from an opinion, without consideration of the pleadings with which it dealt, is to distort it.