The functional test should verify that changing functional status to a 'functioning' one doesn't return the dropdown with reasons for a not working or not in use device.
This test should be based on test case.
Verify that there are valid options for Functionality Statuses
Verify that a user can change the device's functional status
Verify that selecting 'functioning' status doesn't return the dropdown with reasons for a not working or not in use device
Verify that it is possible to cancel changing the status
Verify that a device with valid content is returned after saving changes