Respected Sir, hi I evaluated your query thoroughly.
You are absolutely right at your point of concern.
There are no tests no medicines for this in this world, what at all you can do :
*Try to make her more confident from inside regarding threat of 
syncope in 
  public place.
*Try to locate any precipitating factor if any like if some particular thing 
  preceeds the attack then she has to take care to avoid that only.
*maintain her hydration levels along with BP , Blood sugar levels.
*take adequate sleep of 8 hours.
*Mind 
relaxation techniques , concentration exercises along with 
YOGA are 
  of tremendous help on long term basis if practised regularly.
*Avoid exacerbating factors like anger / 
stress.
*Quit 
smoking / alcohol / consumption of any abuse substances if doing.
 Hope I authentically tried to justify your query at my level best.
 Welcome for any further assistance,
 Thanks for using Health Care Magic and reviewing my answer with such
 patience.
 Wishing your daughter a very happy healthy life ahead.
 Regards.
 Take care of her Bye Dear.