public void ShouldIncreasePaidIn()
            {
                Account sut = new AccountBuilder().WithPaidIn(1000m);

                sut.Credit(250m);

                var expected = 1250m;

                Assert.AreEqual(expected, sut.PaidIn);
            }
            public void ShouldIncreaseBalance()
            {
                Account sut = new AccountBuilder().WithBalance(1000m);

                sut.Credit(250m);

                var expected = 1250m;

                Assert.AreEqual(expected, sut.Balance);
            }