Can dcf give you a drug test?

My son is 20 months old and I have full custody cause his father has a lot of mental issues including anger problems. I had a restraing order too but it ran out. I have tried numerous times to try and involve my sons father in his life (minimally of course) and he goes from wanting to see him to wanting to terminate his rights almost on a weekly basis. I finally decided I had enough and just cut off all communication with him (as he was stalking me on Facebook using family and friends profiles to spy on me) and he wrote an email to my sister last weekend telling me to call him about our son. So I called and he told me he was going to take me to court to get visitation. I told him that with his history of violence and the fact that I had tried to give him visitation would work against him. He started screaming at me and I decided to just hang up. I guess after our conversation he decided to call the DCF hotline and tell them that I was doing drugs and drinking. When they came to my door on Monday I tried explaining everything to them and scheduled a visit for tomorrow morning. Can they do a drug test for this asanine reason? They have proof that he is on medication to prevent his dilusions (which he hasnt been taking and told me so himself) and they have the court documents about his violence and abuse. I'm just trying to live my life and move on from his bull****. I feel like they are allowing him to make me a victim again. He also sent a text to me on Monday saying "whatever happens next isn't my fault". Does anyone have any advice?