The application relates to a packaging system for a hair coloring product containing: i) at least one container (102) holding a composition comprising at least one hair colorant, said composition forming or intended to form a hair coloring product; and ii) at least one test device (20) designed to perform a patch test and incorporating a tube (21) delimiting an internal space containing a dose of said composition, the tube incorporating an outlet aperture (29) and being arranged to cause said composition to be expelled from said outlet aperture (29) in response to excess pressure within the internal space of the tube or when the latter is vented via at least one passage separate from the outlet aperture (29).