Before going to production, you should test everything is working properly with test payments.
Everything will work the same except you won't have to spend real money to test it.
While in test mode (sandbox environement), your normal PayPal account won't work.
You can use the following test account:
email: firstname.lastname@example.org password: 00000000
First, make sure you have added the test API keys from your Stripe account.
At your disposition there is a wide range of fake credit card numbers to try your credit card integration. The full list is available here.
Unfortunately you cannot do fake payments with cryptocurrencies due to the way cryptocurrencies work.