ATM REQUIREMENT TO BE TRANSLATED INTO TEST PLAN AND TEST
CASES
ATM REQUIREMENT AS FOLLOWS:
Requirements Statement for Example ATM System
The software to be designed will control a simulated
automated teller machine (ATM) having a magnetic stripe
reader for reading an ATM card, a customer console
(keyboard and display) for interaction with the customer, a
slot for depositing envelopes, a dispenser for cash (in
multiples of $20), a printer for printing customer
receipts, and a key-operated switch to allow an operator to
start or stop the machine. The ATM will communicate with
the bank's computer over an appropriate communication link.
(The software on the latter is not part of the requirements
for this problem.)

The ATM will service one customer at a time. A customer
will be required to insert an ATM card and enter a personal
identification number (PIN) - both of which will be sent to
the bank for validation as part of each transaction. The
customer will then be able to perform one or more
transactions. The card will be retained in the machine
until the customer indicates that he/she desires no further
transactions, at which point it will be returned - except
as noted below.

The ATM must be able to provide the following services to
the customer:

A customer must be able to make a cash withdrawal from any
suitable account linked to the card, in multiples of
$20.00. Approval must be obtained from the bank before cash
is dispensed.
A customer must be able to make a deposit to any account
linked to the card, consisting of cash and/or checks in an
envelope. The customer will enter the amount of the deposit
into the ATM, subject to manual verification when the
envelope is removed from the machine by an operator.
Approval must be obtained from the bank before physically
accepting the envelope.
A customer must be able to make a transfer of money between
any two accounts linked to the card.
A customer must be able to make a balance inquiry of any
account linked to the card.
A customer must be able to abort a transaction in progress
by pressing the Cancel key instead of responding to a
request from the machine.

The ATM will communicate each transaction to the bank and
obtain verification that it was allowed by the bank.
Ordinarily, a transaction will be considered complete by
the bank once it has been approved. In the case of a
deposit, a second message will be sent to the bank
indicating that the customer has deposited the envelope.
(If the customer fails to deposit the envelope within the
timeout period, or presses cancel instead, no second
message will be sent to the bank and the deposit will not
be credited to the customer.)

If the bank determines that the customer's PIN is invalid,
the customer will be required to re-enter the PIN before a
transaction can proceed. If the customer is unable to
successfully enter the PIN after three tries, the card will
be permanently retained by the machine, and the customer
will have to contact the bank to get it back.

If a transaction fails for any reason other than an invalid
PIN, the ATM will display an explanation of the problem,
and will then ask the customer whether he/she wants to do
another transaction.

The ATM will provide the customer with a printed receipt
for each successful transaction, showing the date, time,
machine location, type of transaction, account(s), amount,
and ending and available balance(s) of the affected account
("to" account for transfers).

The ATM will have a key-operated switch that will allow an
operator to start and stop the servicing of customers.
After turning the switch to the "on" position, the operator
will be required to verify and enter the total cash on
hand. The machine can only be turned off when it is not
servicing a customer. When the switch is moved to the "off"
position, the machine will shut down, so that the operator
may remove deposit envelopes and reload the machine with
cash, blank receipts, etc.

The ATM will also maintain an internal log of transactions
to facilitate resolving ambiguities arising from a hardware
failure in the middle of a transaction. Entries will be
made in the log when the ATM is started up and shut down,
for each message sent to the Bank (along with the response
back, if one is expected), for the dispensing of cash, and
for the receiving of an envelope. Log entries may contain
card numbers and dollar amounts, but for security will
never contain a PIN.