public void CheckActivateMembership() { // This method checks if the ActivateMembership rule works. _iCustomer.Setup(x => x.ActivateMembership(It.IsAny <string>())).Verifiable(); PurchaseOrder purchaseOrder = CreateTestPurchaseOrder(); _rule.ActivateMembership(purchaseOrder); _iCustomer.Verify(x => x.ActivateMembership("46"), Times.Once); }