Restoring a database, changing recovery model
I read that the change in recovery model only has effect after a backup is taken. However, if after the performing the above I do


This is mainly for when you change from simple recovery to full. After changing from simple to full you need to take full backup to take database out of Pseudo simple recovery. Pseudo simple recovery means even if database is in full recovery model it will behave like simple and automatic checkpoint would happen and you will not get point in time recovery. The moment you take full backup you tell SQL database engine that Now I would manage log truncations by taking transaction log backup.


  Do I need to take a backup to actually change the recovery model of my test database to simple?


For your case since you are changed recovery model to simple so you DONT need to take any backup to actually make it behave in simple recovery. I am not talking about normal backup you take for your dev databases. You should continue taking normal full backup of your dev databases.