Functional test sequence Refei to the eoffee distributor study. The expression of our dient' s needs ean be summarized to 'make money by providing eoffee'. Mter an initial study, we propose the following informal speeifieation to hirn:

"To obtain a eoffee, the user has to introduee at least 1$, then validate by pressing on the 'Coffee' button. The ehange is then given and the eoffee served. If the user has not provided enough money before validating, the money is returned and the eoffee is not served. The money entered is also returned if we press on the 'Caneellation' button before 'Coffee'.

Furthermore, the distributor eontains a eertain number of eoffee doses. The money introdueed has to be returned if there are no more doses in reserve."

Using this informal specification, deduee a funetional test sequenee of the system to realize.

This sequenee firstly serves the designer and the dient for the verifieation of the designed system. By defining the input/output relationships, the test sequenee also provides the distributor' s utilization scenarios. From this point of view, the definition of the test sequenee after the specifieation of the produet and its presentation to the c1ient eonstitute a means of dialogue which permits the verifieation and the good understanding of needs.