2.2.1.1 Black box testing - without user involvement

The so-called ``functionality testing'' is central to most testing exercises. Its primary objective is to assess whether the program does what it is supposed to do, i.e. what is specified in the requirements. There are different approaches to functionality testing. One is the testing of each program feature or function in sequence. The other is to test module by module, i.e. each function where it is called first.

The objective of volume tests is to find the limitations of the software by processing a huge amount of data. A volume test can uncover problems that are related to the efficiency of a system, e.g. incorrect buffer sizes, a consumption of too much memory space, or only show that an error message would be needed telling the user that the system cannot process the given amount of data.

During a stress test, the system has to process a huge amount of data or perform many function calls within a short period of time. A typical example could be to perform the same function from all workstations connected in a LAN within a short period of time (e.g. sending e-mails, or, in the NLP area, to modify a term bank via different terminals simultaneously).

The aim of recovery testing is to make sure to which extent data can be recovered after a system breakdown. Does the system provide possibilities to recover all of the data or part of it? How much can be recovered and how? Is the recovered data still correct and consistent? Particularly for software that needs high reliability standards, recovery testing is very important.
The notion of benchmark tests involves the testing of program efficiency. The efficiency of a piece of software strongly depends on the hardware environment and therefore benchmark tests always consider the soft/hardware combination. Whereas for most software engineers benchmark tests are concerned with the quantitative measurement of specific operations, some also consider user tests that compare the efficiency of different software systems as benchmark tests. In the context of this document, however, benchmark tests only denote operations that are independent of personal variables.