Performing a system test

The difference between the testing done at this stage and the testing done during the development phase is that we are now testing the application as a whole, as well as in conjunction with other applications. We also carry out tests that can only be done once the application coding has been completed because we need to know how the whole application performs, and not just a portion of it.

The tests performed during this phase are:

User testing--Testing the application for functionality and usability.
Integration testing--The new application is tested together with other applications to see if they interface as expected.
Performance or stress testing--The application is tested using real production data or at least real production data volume to see how well the application performs when there is high demand.

The results of the user and integration tests need to be verified to ensure that they are satisfactory. In addition, the performance of the application must match the requirements. Any issues coming out of these tests need to be addressed before going into production. The number of issues encountered during the testing phase are a good indication of how well we did our design work.