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Does the system work as expected?. The Systems Life Cycle: Development and testing. So far…. You have learnt about the stages involved in Analysis Design So what comes next... Creating the system Testing the system Improving the system. Testing. - PowerPoint PPT Presentation
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Does the system work as expected?
You have learnt about the stages involved in Analysis Design
So what comes next... Creating the system Testing the system Improving the system
Each time that testing shows a problem there will need to be further... Analysis Development Testing
This cycle can happen many times until the system is perfect
Once designed by the systems analyst these must be created by the programmer
The programmer will follow the system analysts designs. E.g Using the recommended programming
language Using the recommended software
Some businesses are able to use existing software to create their desired result Access and Word for example could be used
to mail letters to clients
Other businesses have to have a programme specially written for them this is know as: Purpose built - OR - Bespoke
The systems analyst will have created a test plan.
They will also have prepared a set of test data together with a list of expected resultsTest Test
DataExpected results
Actual results
Comments
Test student D.O.B in school
database
16/04/1992 Accepted
09/09/2007 Accepted
99/99/9999 Rejected
Usually three types of data are tested Normal – data which should be acceptable
or valid in the system.
Extreme – only used when a range of data is used. Extremes of the range are tested.
Abnormal – Data which is not acceptable or valid in the system.
Lets look back at the data on the previous slide – which is which?
Copy the test plan table and try to come up with some more tests that you’d recommend a school tried on their new system.
Test Type of
data
Test Data
Expected
results
Actual results
Comments
Test student D.O.B
in school
database
Normal 16/04/1992
Accepted
Extreme 09/09/2007
Accepted
Abnormal
99/99/9999
Rejected
Data which is already used by the business can be used to test the system.
The data output from the new and old systems should match.
If there are differences then there is a problem to be found and solved.
After the test plan has been fully tested the systems analyst will have to check the results
Are there any problems which need to be solved?
Sometimes single stepping is used. This is when a system can be run just one step at a time until the problem is found
Introducing the system to the place it will be used
Once the system is ready there are 4 main ways of implementing it. Parallel running Direct changeover Phased implementation Pilot running
Switch off the old system and switch on the new.
Simplest scenario Old systems switched off, new
system takes over completely Non critical systems only the new system replaces the
old system in one go saves money in wages/very
fast method of implementation
BUT if anything goes wrong you
don’t have the old system to fall back on
Cannot go back to old system if any problems
Both old and new systems run side by side till new system is working properly
Necessary in critical situations If the new system breaks
down you still have the old system as a backup
BUT It can be a slow process/all
tasks have to be performed twice
Expensive in terms of resources (may need two sets of staff)
New system is brought in one section at a time
Can ensure each part of new system works properly before changing the next part
Eg new library systemBUT Takes longer than
direct changeover If new system
unsuccessful, may lose some data
Eg in large banks or corporations
One branch changes to new system, identifies any problems
Other branches function as normal
Problems can be identified & solved before new system is rolled out to all branches
BUT If new system
unsuccessful, may lose some data
Direct changeoverThe old system is scrapped and immediately
replaced by the new system. With this option there is a danger that there may still be problems with the new system. Even though it is the most risky type of changeover, many companies use this method.
Phased changeoverThe change over is split into phases or stages.
Each stage is introduced one at a time and the old system is kept running to do the remainder of the tasks that have not yet been changed.
Parallel runningRunning both the old and new system until you are
certain the new system is working correctly. Parallel running is likely to be the most expensive as it involves doing the work twice for a period of time. However, it is the safest. If there are any bugs in the new system, you can always go back to the old system while the problems are corrected.
Pilot changeoverChanging over in a small part of the company to start
with. Only when the system is deemed satisfactory will it be rolled out to the rest of the organisation. A supermarket introducing a new 'self-scanning' system might choose to introduce it in two or three stores at first. This is a pilot changeover.
The analyst can not stay with the business for ever – a guide to help the new users
Systems usually have two types of documentation Technical documentation User documentation
User manual Technical manualThe purpose of the program The purpose of the program
Loading and running the program
Hardware and software requirements
How to use the program: entering data, saving, editing, sorting, printing...
Limitations of the program
Input and output formats File structures
Hardware and software requirements
Program coding
Limitations of the program Variables
Error messages Dataflow diagrams
Troubleshooting Validation routines
Frequently asked questionsProgram and system flowcharts