There is no way for you to "test" a service or the checkout process. You can certainly purchase the service for yourself and utilize it, which you will be charged in full.
Please do not purchase the service, go through the checkout process, then immediately cancel and request a refund. This affects your payments and the workers payments. It also disrupts the organization and process for the workers - who will then be handling your future customers.
Please see this article for more info about checkout: http://support.workify.co/hc/en-us/articles/231273968-What-happens-when-my-customer-buys-a-service-
If you have any questions on the services, feel free to ask!