Development and Testing

Development and Testing

 

Development and testing

This phase is where the system starts to be written by the software programmers. They follow the requirements specification from the design stage and start to create the new system.

The main things that take place during this phase are:

• The programmers write and test the code for the system
• A team ensure that the hardware and software required to run the new system are purchased and in place.
• A team of testers are assembled in readiness to test the new system. They start to write a test plan which details all of the tests that they will carry out.

A test plan is usually written whilst the system is being developed. The test plan will contain details of every single thing that needs to be tested.

For example:

• Does the system open and close properly?
• Can data be entered?
• Can data be saved?
• Can reports be printed?
• When you do something wrong, does an error message appear?
• Is invalid data rejected? E.g. if you are not allowed to enter an amount above £1,000 on the system then a value of 1,001 should not be accepted (i.e. does the validation work?)

Test plans are very detailed, and contain many tests. Each test is specified very precisely.

A typical test would contain:

• Details of what is being tested
• The test data to use
• What is expected to happen when the test is performed

Selecting Test Data

When choosing what data to use to test a system, you need to think about why we are testing the system: to see if it works, and to check it doesn't break.

Normal Data Values

This is data that would normally be entered into the system.

The system should accept it, process it, and we can then check the results that are output to make sure they are correct.

 

Extreme Data Values

Extreme value are still normal data. However, the values are chosen to be at the absolute limits of the normal range.

Extreme values are used in testing to make sure that all normal values will be accepted and processed correctly.

 

Abnormal Data Values

This is data that should not normally be accepted by the system - the values are invalid.

The system should reject any abnormal values.

Abnormal values are used in testing to make sure that invalid data does not break the system.

 

 

When is the System Tested?

Testing is normally done in two stages...

The first phase of testing is done by the designers and engineers who created the system, usually before the system is delivered to the customer.

The test data that is used in this first phase is similar to data that would be used by the actual customer.

The second phase of testing is done after the system has been delivered and installed with the customer.

The data used in the second phase is usually 'live' data - data that is actually part of the customer's business / organization.

How tests are carried out.

1. A test table is created which shows the test data to be used and the results expected
2. The data is then input into the system
3. The results of each test is recorded
4. The actual results are compared with each expected result
5. Any differences show the limitations of the system.

 

What Happens if the System Fails Some Tests?

The whole point of testing is to try and find areas that don't work as they should, or areas that can be improved.

If any failures are found, the systems analyst goes back and does some further research, analysis and design to fix these areas.