Unit Testing: Testing the Source Code Piece By Piece

Software consists of many different applications which have to be tested independently for security, performance, functionality, usability, reliability, efficiency, portability and maintainability etc. A unit is the smallest part of the software application. Each of the modules of the software comprises of a number of individual units. There are a large number of such units in the application software. Software testing can either be done for an individual unit or a group of units. In case there is a problem in the group testing, the testing has to be done at unit level. Unit testing is the method of making sure that each of the individual units is working properly in isolation. In this, testing is carried out on the minimal software component or module. They get integrated once the module testing is completed.

One of the many benefits of unit testing is the ability of the software programmer to change or improve the way the computer program is read without affecting the functionality/ performance of the program. Test cases are prepared for all the functions of the program and this facilitates easy identification and correction of the problems in case of changes made. It is possible to test the units first and eliminate all the bugs that appear during this testing. The entire integrated program can be tested after debugging all the unit modules. This makes the process easier, faster and efficient.

The test report based on unit testing is more or less similar to a written report on the system. This is very useful for the programmers because whenever they are interested in knowing the functionality a unit provides they only have to look at the documentation provided by the unit tester. Unit testing comprises of many unit test cases and these are critical to the unit's ultimate success. The test cases show characteristics that indicate negative behavior in the software or inappropriate functions.

Unit testing alone will not be sufficient for software approval; however, this combined with other testing types will be very effective. It is not possible to trap all errors in the software either by software testing or unit testing. Unit testing is useful in testing the functionality of the unit. It may not be possible to detect integration or performance problems during unit testing.

Unit testing can be carried out either manually or through automated tests. The primary objective of unit testing is to pinpoint the defects in the software, isolate that unit and correct it.