Computer Science and Software Engineering 371

Software Requirements and Specification

Fall 2005

Exam 2 Review Solution

1. (a) Since Feature 2 was a high-risk proposition, it is likely that Feature 3 was chosen in order to increase the possibility of getting one important feature implemented.

(b) The description of Feature 5 (New project wizard) sounds like it could be dependent on Feature 3 (Ability to clone a project), Feature 5 would have to be done first.

2. Consider the use case below.

Name of Use Case	ATM Checking Withdrawal
Brief Description	Withdraw money from a checking account using an ATM
Actor(s)	User, Bank database
Basic Flow	1. The user enters the amount of the withdrawal request within 60 seconds. 2. The ATM gives the user the desired amount on money.
Alternate Flow(s)	1. The user does not provide an amount within 60 seconds, and is then prompted, asking if more time is desired. There are two possible outcomes: a. If the user answers “yes”, step 1 starts again from the beginning b. If the user answers “no” or does not respond within 60 more seconds, the withdrawal is cancelled. 2. If the user enters an amount greater than the balance on that account, the user prompted for a new amount (as in step 1). 3. The user presses the cancel button instead of entering an amount, and the withdrawal is cancelled.
Pre-conditions	The user has already specified that withdrawal from their checking account is desired, and the ATM screen is already prompting the user for an amount to withdraw.
Post-conditions	The user received prompt asking if additional transactions are desired.
Special requirements	none

Step 1: Identify the Use-Case Scenarios

Below is a depiction of the flow as shown in the textbook’s format; a state diagram could also be used.

Step 2: Identify the Test Cases

Each flow edge from the figure step 1 needs to be involved in at least one test case. Scenario 3 (where the user is asked for more time but declines, through either action or inaction) needs two test cases because of the two ways involved.

Test Case Id	Scenario	Description	Expected Result
1	1	User successfully withdraws money	amount requested is paid in cash
2	2	User takes too long to enter amount but asks for more time	user is asked for withdrawal amount again
3	3	User takes too long to enter amount but answers request for more time in the negative	withdrawal request cancelled
4	3	User takes too long to enter amount and also to request for more time	withdrawal request cancelled
5	4	User asks for more money than in the bank account	user is informed of the problem and asked for withdrawal amount again
6	5	User presses cancel button	withdrawal request cancelled

Step 3: Identify the Test Conditions

Step 4: Add Data Values to Complete the Test Case

Test Case Id	Scenario	Description	Condition: cancel button pressed	Condition: time taken to enter withdrawal amount	Condition: amount requested <= account balance	Condition: time taken to enter response to request for more time	Condition: response to request for more time	Expected Result
1	1	User successfully withdraws money	No	<= 60 sec	Yes	N/A	N/A	amount requested is paid in cash
2	2	User takes too long to enter amount but asks for more time	No	> 60 sec	N/A	<= 60 sec	Yes	user is asked for withdrawal amount again
3	3	User takes too long to enter amount but answers request for more time in the negative	No	> 60 sec	N/A	<= 60 sec	No	withdrawal request cancelled
4	3	User takes too long to enter amount and also to request for more time	No	> 60 sec	N/A	> 60 sec	N/A	withdrawal request cancelled
5	4	User asks for more money than in the bank account	No	<= 60 sec	No	N/A	N/A	user is informed of the problem and asked for withdrawal amount again
6	5	User presses cancel button	Yes	N/A	N/A	N/A	N/A	withdrawal request cancelled

3. (a) A request for change should be submitted through the control change system mechanism. The change control board (CCB) should then decide whether or not to make the change, and if so, where the change should originate in the development artifacts.

(b) Approval of a new feature means that the vision document must be changed, which in turn changes the use cases, design, code and test cases.

4. For agile requirements, test cases must be planned before coding. Testing is actually performed using an automated tool.