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7.3 development and testing



Once the new system has been designed, it needs to be developed and tested.

Testing and development is a continuous process – you don’t develop the whole system and then test it! You develop the system a piece at a time and then test that bit.

Development of the new system

When developing the new system you will need to create.

Data and file structures


Validation routines


Input Methods


Output formats


Types of testing

Modular Testing

It is common for each part of a system to be developed independently, with each part being tested separately as they are developed. This is known as modular testing.

Whole System Testing

Once the system is complete, or near complete, whole system testing is conducted. This is done to ensure that all of the component parts work well together and any ‘bugs’ in the system are ironed out. This phase usually includes the use of live, or ‘real’ data, rather than test data and is usually regarded as the Beta Testing phase.

Testing Data

When testing it is important to use each of the following types of data:

Normal data

This data is valid data that you would expect your system to handle. E.g. Age – 25

Abnormal Data

This is invalid data that your system should reject E.g. Age – 100000

Extreme Data

This is data at the verge edge of acceptable values – E.g. Age = 110. This should normal prompt the user to check the input value is correct.

Live Data

This is a wide variety of real data taken from the current or past system and is designed to be used to check that your system is running correctly.