What is the test for recoverable costs in a personal injury action?

Under section 1032, "a prevailing party is entitled as a matter of right to recover costs in any action or proceeding." ( 1032, subd. (b).) Section 1033.5 identifies which costs are allowable ( 1033.5, subd.(a)) and which costs are prohibited unless otherwise authorized by law ( 1033.5, subd. (b)). "An item not specifically allowable under subdivision (a) nor prohibited under subdivision (b) may nevertheless be recoverable in the discretion of the court if 'reasonably necessary to the conduct of the litigation rather than merely convenient or beneficial to its preparation.' ( 1033.5, subd. (c)(2).)" (Ladas v. California State Auto. Assn. (1993) 19 Cal.App.4th 761, 773-774 (Ladas).)