public void TestDelPrivateState()
        {
            ChaincodeStub stub = new ChaincodeStub("myc", "txId", handler.Object, new List <ByteString>(), null);

            stub.DelPrivateData("testcoll", "key");
            handler.Verify(a => a.DeleteStateAsync("myc", "txId", "testcoll", "key", token));
            try
            {
                stub.DelPrivateData(null, "key");
                Assert.Fail("Null collection check fails");
            }
            catch (ArgumentException)
            {
                //ignored
            }

            try
            {
                stub.DelPrivateData("", "key");
                Assert.Fail("Empty collection check fails");
            }
            catch (ArgumentException)
            {
                //ignored
            }
        }