Yes, we will need your assistance in testing the project, if that is possible. Even though we have systems in place for testing and quality assurance, the way we think about and use your app is different from the way you would. Given that you specified the project and that you are the best person to know what you want, it's likely that you will utilize and interact with what we've produced in ways that we couldn't have foreseen. Even if everything works flawlessly when we give it over to you, you will need to double-check that everything is functioning as intended before you can sign off on the job with confidence that we have completed the project according to your requirements. The process of testing and obtaining sign-off will take some time commitment towards the conclusion of a project, and maybe at intervals during the project's lifespan as well – so make sure to block out some time in your calendar for when it is required.