5 - Unit Testing

Summary

(The Programmer) personally defines the functional and performance specifications, designs the program, codes it, tests it, and writes its documentation…. They need great talent, ten years experience and considerable systems and applications knowledge, whether in applied mathematics, business data handling, or whatever!

Fred P. Brooks

Overview

The objective of Unit Testing is to ensure that reliable program units are produced that meet their requirements. The process is also intended to identify errors in program logic. Unit Testing is conducted by the development team under the supervision of the Development Team Leader. Typically, the software engineer or programmer who coded the unit will design and run a series of tests to verify that the unit meets its requirements. Unit Testing may also be termed component testing.

Each unit should be tested individually and in isolation (although it may be necessary to employ a test harness) by exercising its inputs and observing its outputs or behavior. It may also be possible for the unit to be tested using the facilities available in the development environment (such as stepping through the statements of code using a debugger). Once confidence has been established in the unit, it should then be tested in collaboration with other interoperating units.

Unit Testing is typically a White Box Testing activity, based primarily on the functional and data requirements expressed in the requirements specification for the Application Under Test (AUT), as well as any supplementary material (such as design documentation, user guides, or prototype code).