Testing and Debugging
Testing and debugging is a vital component of the waterfall approach. Everything is the system is tested and problems are worked through. Testing of all programs that are written during the design process is essential. The final test will work out all bugs within programs, so that users of the system do not encounter these bugs when the system is installed. If the bugs are not worked out the installation process will be slowed and time and money will be wasted. During a system test, users enter data, including samples of actual, or live data, perform queries, and produce reports to simulate actual operating conditions. (Rosenblatt, 10.18) Testing of individual applications rather than testing the system as a whole is unit testing. The programs must be tested by programmer to make sure that they can communicate with other applications and individual files before they are implemented into the system.
Installation
The final phase of the waterfall approach is to install the system after testing and debugging. The installation process mainly includes installing the system in place of the previous, but also training of new users to the system. Users of all types must be trained in the system, from IT support and general users, all the way up to management. Installation may be handled in various ways depending on costs and time. A direct cut over is an extremely high risk process of installing a new system, but uses up the least amount of money. During a direct cut over the system is install straight away without installing it in pieces or over a period of time. A parallel installation is a less risky option for installation but takes more time a money to install. During parallel installation the new system is brought in as the old system is running. They are run side by side while errors and bugs are looked for. Both systems are running at the same time so this is a very costly operation, but the safest. Phased deployment is a third option for installing a system. Phased installation brings the new system in step by step while the old system still runs. This is a combination of direct and parallel installation and is relatively safe, but expensive still because the old system and parts of the new system will be running at the same time.