The nShift Checkout configuration interface has a built-in test panel with the option to enable Developer mode. Use the test section when creating a new Checkout configuration or editing an existing one to preview the Checkout widget. 

Using the test panel

The test feature is available on all screens when editing or creating a new configuration. 

1. Click Change test input on the right side of the screen to open the test panel
   
   
   
   
2. Fill in the parameters with test data. On top, you have all the Mandatory parameters followed by System parameters and Custom parameters. The parameters in the test panel reflect the parameters you enabled in the Parameters section. 
   
   
   
   
3. When you modify the test data, the widget preview will update accordingly. This allows you to see how changes to the configuration, delivery options and rules affect the widget.

Developer mode

1. To enable Developer mode, set the toggle switch at the bottom of the test panel to active.
   
   
   
   
2. This will open a Developer tools section below the widget preview.
   
   
   
   
3. The Developer Tools allows you to change widget settings, and see widget requests, responses, and results. The request and response will be based on the parameters in the test panel and the JSON will update when you change the parameters.