# Lists available collection names.
	#
	# Returns `null` if an error occured. See `Sys::last_mongoc_error`.
	#
	# ~~~
	# var client = new MongoClient("mongodb://mongo:27017/")
	# var db_suffix = "NIT_TESTING_ID".environ
	# var db_name = "test_{db_suffix}"
	# var db = client.database(db_name)
	# db.collection("test").insert(new JsonObject)
	# assert db.collection_names.has("test")
	# ~~~
	fun collection_names: Array[String] do
		var res = new Array[String]
		var nas = native.collection_names
		if nas == null then return res
		var i = 0
		var name = nas[i]
		while not name.address_is_null do
			res.add name.to_s
			name.free
			i += 1
			name = nas[i]
		end
		return res
	end