Most sensors have a way to manually test (button?).
Once enabled (Device Settings --> Advanced), you should see an event in the activity card (tap on tab lower left hand corner). Also, a push notification will be sent if you have that enabled.
One known firmware defect is when enabling/disabling the rain senor in the app, the setting won't get picked up until the device is power cycled. This has been fixed in the firmware, just waiting for the right time to deploy the patch.
Hope this helps.