In order to test the Stripe payment gateway, you will need to verify your Stripe account is in 'test' mode, and get test API credentials. You can find the Test Secret Key & Test Publishable Key in your Stripe Account Settings area:
Deals Stripe Settings
From within Stripe Payment Gateway Extension settings area, enable the Stripe option. If Stripe does not show up under Payment Gateways, this means the Stripe extension has not been installed and activated.
test API keys in Deals >
Settings > Payment Gateways - Stripe Settings within their respective fields and hit 'Save Changes'.
Now in test mode, add a product to your cart and proceed to checkout.
You can use the card number 4242424242424242 with any CVC and a valid expiration date (any date in the future).