BitPay is the first and most experienced company in bitcoin payments. BitPay builds powerful tools for secure bitcoin payment acceptance, savings, and spending.
Begin by activating the payment gateway under Setup > Payments > Payment Gateways and choose BitPay from the All Payment Gateways tab.
Once activated, you can then enter the configuration details explained below.
The API Key is automatically generated when saving the gateway configuration. This field should be left empty to automatically generate the value. When changing from Test Mode to Live, this field should be emptied.
The Pairing Code is automatically generated when saving the gateway configuration. This field should be left empty to automatically generate the value. When changing from Test Mode to Live, this field should be emptied. This pairing code should be entered into your BitPay account. This is done in Payment Tools > Manage API Tokens.
The transaction speed setting determines how quickly an invoice payment is considered to be "confirmed," which would be the status at which you would fulfill and complete the order.
More information on the Transaction Speeds and what they mean can be found in the BitPay documentation: https://support.bitpay.com/hc/en-us/articles/202943915-What-does-the-Transaction-Speed-setting-do
Check this to enable Test Mode using BitPay.