Activate test mode for Shopify Payments

1. In the Shopify Payments section, click Manage.

2. In the Test mode section, select Enable test mode.

3. Click Save.

Next steps:

You can create orders and then simulate transactions by using a test credit card number. There are test numbers to create successful transactions, failed transactions, and transactions in different currencies.

Simulate successful transactions

To simulate a successful transaction, use the following information when you are asked for credit card details at checkout:

• Name on card: Enter at least two words.
• Expiry date: Enter any date in the future.
• Security code: Enter any three digits.
• Card number: Use any of the following numbers:

Simulate failed transactions

If you want to view the credit card error messages that might be displayed to a customer during checkout, then you can use these test credit card numbers to simulate different failed transactions:

• Use credit card number 4000000000000002 to generate a card declined message.
• Use credit card number 4242424242424241 to generate an incorrect number message.
• Use credit card number 4000000000000259 to simulate a disputed transaction.
• Use an invalid expiry month, for example 13, to generate an invalid expiry month message.
• Use an expiry year in the past to generate an invalid expiry year message.
• Use a two-digit security code number to generate an invalid security code message.

https://help.shopify.com/en/manual/payments/shopify-payments/testing-shopify-payments