Alford Academy Business Education and Computing 1

Advanced Higher Computing

Based on Heriot-Watt University Scholar Materials

Implementation and Testing

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Lesson Objectives

Implementation, Testing, Evaluation and Maintenance

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ImplementationThis is the stage at which the software is coded, the user interface designed, hardware is set up and any legacy files are converted to the formats needed by the new system

Coding

Need to select a programming language in which to implement the code. The language needs to suit the problem:

Procedural (Pascal, Comal, etc)

Declarative (Prolog)

Event Driven (VBasic, etc.)

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TestingTesting must be systematic – this means that it is carried out in a rigorous and structured manner.

Large-scale system testing

ATM

VERIFY CARD ENTRY

HANDLE MENU SELECTION

HANDLE CASH AND RECEIPT OUTPUTS

Modular approach breaks the large problem into smaller subsystems

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Testing

SUBSYSTEMS are coded and MODULES are tested independently

VERIFY CARD ENTRY

READ USER ACCOUNT DATA

CONTACT MAINFRAME

ACCEPT OR REJECT CARD MESSAGE

ACCESS MAGNETIC

STRIPE DATA

GET PIN NUMBER

VERIFY ACCOUNT DETAILS

VERIFY CARD ENTRY SUBSYSTEM

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TestingVERIFY CARD

ENTRY

READ USER ACCOUNT DATA

CONTACT MAINFRAME

ACCEPT OR REJECT CARD MESSAGE

SUB-SYSTEMS are coded and MODULES are tested independently

ACCESS MAGNETIC

STRIPE DATA

GET PIN NUMBER

VERIFY ACCOUNT DETAILS

VERIFY CARD ENTRY SUB-SYSTEM

SUB-SYSTEMS are then integrated and the whole system is tested

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Test StrategiesVERIFY CARD

ENTRY

READ USER ACCOUNT DATA

CONTACT MAINFRAME

ACCEPT OR REJECT CARD MESSAGE

ACCESS MAGNETIC

STRIPE DATA

GET PIN NUMBER

VERIFY ACCOUNT DETAILS

Without knowing the detail of the module code, test cases are built to test the inputs and outputs of the module. For the highlighted module, what test cases would you choose?

Black Box Testing

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Test StrategiesVERIFY CARD

ENTRY

READ USER ACCOUNT DATA

CONTACT MAINFRAME

ACCEPT OR REJECT CARD MESSAGE

ACCESS MAGNETIC

STRIPE DATA

The structure of the code is examined and test cases are used to check that the logic of the code is correct. What test cases would you use here?

White Box Testing

GET PIN NUMBER

validPin = false

Do

pin = inputbox(“Enter pin number”)

if Len$(pin) < 4 then

msgbox(“invalid pin”)

elseif not Int(pin) then

msgbox(“invalid pin”)

else

validPin = true

Loop until validPin = true

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Acquisition of hardwareUpgrade to an existing system

Purpose built site and completely new system

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Changeover StrategiesHow will the new system be brought in to replace the old system?

Parallel conversion:- run the old in parallel with the new for a period of time until you are satisfied that the new system is reliable and error-free.

Phased conversion:- Same as parallel only on a smaller scale. Run the new system in phases and as each is tested and is proven to be robust, introduce a new phase.

Pilot conversion:- Restrict to a section of the old system – if the new section works then changeover.

Direct conversion:- Immediately convert to the new system – also known as the ‘big bang’

Combined conversion:- Involves a mixture – some parts of the old system are immediately changed over while others are phased in or piloted

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EvaluationKey question – is the new system FIT FOR PURPOSE ie does it meet the original specification of the ORD and allow the client to operate successfully

Methods:- questionnaires, interviews, observations, bring in consultants who specialise in evaluations, data logging.

Evaluation Criteria

• the time it takes to install a piece of equipment

• the number of errors an operator makes while doing a specific task

• the time it takes an operator to complete a task

• the number of times a computer crashes or hangs

• the number of phine-calls made to a help-line

• the number of times a user consults a manual

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Maintenance

This comes into effect once a system has passed its ACCEPTANCE TEST

Perfective – Adaptive - Corrective

Preventive Maintenance:- deals with updating the system documentation and changing the structure of the software to ease future maintainability.

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Percentage Costs of Development Phases

3%

3%

5%

7%

15%

67%

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Activities

Answer Review questions 14-18 on pages 23 and 24 of the Scholar booklet

Do the End of Topic Test on pages 24 and 25 of the Scholar booklet

Homework – Read pages 19-23 of Scholar booklet and begin to prepare your own summary notes – you may wish to copy some of the text and diagrams from the Scholar website