You can switch to the test mode using the drop-down option at the top of the Dashboard.
Razorpay test mode is a replication of Razorpay in a sandbox environment. This allows you to test all aspects of your integration before you go live. Test mode is available to you as soon as you complete the sign-up process. You can use Test mode as long as you want.
Actions taken in the test mode have no consequences in your live environment. Transactions and entities created in the test mode do not appear in the live mode. No real money is used in the test mode.
You have to generate separate API keys for live and test modes. Refer to the API Keys section for more details about API keys.
After you have thoroughly tested your integration, you can switch to the Live mode and start accepting payments from customer.
Payments made by your customers are settled to your account according to your settlement cycle.