public void AccountSubscribeToCommissionFail()
        {
            //Arrange
            CommissionAccount acc = new CommissionAccount("123", 10, Currency.AUD);

            //Assert
            AccountManager nothing = null;
            var            ex      = Assert.Throws <ArgumentNullException>(() => acc.SubscribeToCommission(nothing));

            Assert.AreEqual($"{ExceptionMessages.AccountSubscribeNullParam() + Environment.NewLine}Parameter name: accountManager", ex.Message);
        }