With help of Resty it is possible to solve the task and create test users (Scala):
val authToken = resty.text("https://graph.facebook.com/oauth/access_token?client_id=your_app_id" +
"&client_secret=your_app_secret&grant_type=client_credentials")
val jsonResource: JSONResource = resty.json(
"https://graph.facebook.com/your_app_id/accounts/test-users?installed=true&name=Abra+Kadabra&" +
"locale=en_US&permissions=read_stream&method=post&access_token=" + URLEncoder.encode(accessToken.toString.split("=")(1)))
val token = URLEncoder.encode(jsonResource.get("access_token").asInstanceOf[String])
val userId = jsonResource.get("id").asInstanceOf[String]