Testing and using flows is much like testing and using forms . Please refer to the forms chapter for the bulk of information on this topic. We'll only discuss the differences here
Testing Flows
When you click Test 
icon will display your flow in “Use Mode”—in other words, the flow will appear and behave exactly as it will when users access it. To test the flow, just complete it as your users would and click Submit. Test mode allows you to view your flow as it would appear on a desktop, iPad or iPhone. Refer to Testing Forms for more information about Test Mode views.