You want to make sure that purchases work correctly. Apple provides a sandbox environment that allows you to test your app In-App Purchases. The sandbox environment uses the same model as the App Store, but does not process actual payments. Transactions return as if payments were processed successfully. It is a requirement to test In-App Purchases in a sandbox environment before submitting them for review by Apple.
When testing in the sandbox environment, you'll need to create a separate user test account that is different from your current iTunes Connect account. Using your current account is not allowed to test your store in the sandbox.
While logged into your iTunes Connect account, you'll have to select the Manage Users link from the home page. Select Test User on the Select User Type page. Add a new user and make sure that the test account uses an e-mail address that is not associated with any other Apple account. All test accounts should only...