White Box Testing

White box testing

White box testing (also referred to as glass box testing) is a software testing technique in which the test data is carefully selected in order to test, as fully as possible, every possible execution path through the software unit (or subsystem) under test. A detailed knowledge of the algorithms used to implement the unit is essential in order to ensure that the tester understands the program logic involved, and can ascertain that every possible scenario is examined. The tester must be thoroughly familiar with the relevant programming language, and be able to determine whether or not the test results match those required by the specification.

This type of testing relies quite heavily on the availability of adequate documentation, and the use of clearly-written and well commented program code. It is also a fairly resource-intensive process, and is most frequently used for low level testing (typically unit and integration testing). With this type of testing, all of the execution paths through the unit (or between units if integration testing is being undertaken) will be tested. The test cases are typically designed to carry out control flow testing, data flow testing, and branch testing.