To test paypal payments you need to:
Create developer account
Add seller and buyer in developer sandbox
Add seller and buyer¶
Go to Dashboard->Sand box->Accounts. Create business (seller) and personal (buyer) accounts. It’s recommended to don’t use non-ascii symbols in account information (address, name etc.)
Add some money to buyer (type amount in according field).
Go to http://sandbox.paypal.com and login as seller. May be you will be forced to apply unconfirmed ssl certificate.
Go to Profile.
Copy protected seller code.
Install payment_paypal module
Go to Settings->Payments->Payments->Paypal.
Enter here Paypal Email ID - it is seller account.
Enter Paypal Merchant ID - paste protected seller code.
Set price list currency same as in paypal account.
Open web shop. Buy some goods and pay with paypal. When you will be redirected on paypal page use buyer login and password.