To be able to do test purchase you need to specify your sandbox email address of PayPal under Settings >> Payment Integration Settings. Please follow this steps to create your sandbox account:
- Log in to the Developer site at https://developer.paypal.com and navigate to Applications > Sandbox Accounts.
- Click the Create Account button and populate the following fields:
Tick either the Personal or Business radio button.
Enter a valid email address of your choosing.
The email address doesn't need to be a real email address; the Sandbox doesn't send any email outside of the Sandbox environment. Email to Sandbox accounts, generated as a result of your test API requests, are listed on both the Notifications tab on the Developer site, as well as on the Sandbox test site.
Use the assigned email value to reference this test account in your API calls, and to log in to the Sandbox site when you want to review the details associated with the account.
The password must be 8-20 alpha-numeric characters in length.
First and Last names
The optional name fields accept alpha-numeric characters.
While this field is optional, it's a good idea to create test accounts with positive bank balances. Enter an integer value between 1 and 5000.
Bank verified account
You should create both Verified and Unverified test accounts so you can fully test your application.
Select payment card (Personal account type only)
Test payments made with different payment cards by selecting either Discover or PayPal.
Credit card type
You must select a single credit card type for each test account. The Sandbox associates a mock credit card number with the account.
Log in with PayPal (Business account type only)
Use the Notes field to keep track of the test account details.
Click Create Account after completing the account details.
You need to create at least two accounts to be used as the seller and the other one as the buyer/customer. As a seller account you need to create its account type as "Business (merchant account)". Click this link for more details https://www.x.com/developers/paypal/documentation-tools/ug_sandbox.
Here is how to do a test purchase