Ensuring Sufficient Supply of Testing Act This bill expressly authorizes the Department of Health and Human Services (HHS) to enter into certain contracts and cooperative agreements with clinical laboratories as part of maintaining the Strategic National Stockpile. The Strategic National Stockpile consists of drugs, vaccines, medical products, and other supplies that may be deployed to respond to bioterrorist attacks or other public health emergencies. Current law permits HHS to enter into specified types of contracts and cooperative agreements with vendors (e.g., manufacturers and distributors of medical products) for managing inventory of and ensuring production capacity for supplies needed for the stockpile. The bill specifies that clinical laboratories may participate as vendors in those types of contracts and agreements.