what is role of ZnCl2 in lucas test? and the mechanism for the reaction

Lucas' reagent is a solution of zinc chloride in concentrated hydrochloric acid, used to classify alcohols of low molecular weight. The reaction is a substitution in which the chlorine replaces the hydroxy group. the zinc ion complexes with the hydroxy group (by accepting a lone electron pair from O of -OH), making it a better leaving group. The remaining carbonium ion then combines with the chloride ion to form an alkyl halide.