For a long time, the majority of the programmers believed that programs are only written to be read by a computer. It was also their opinion that the only way to test a program is to execute it on the machine for which it was designed. This attitude often led towards badly structured, illegible, and nearly unchangeable programs.
But what if a programmer knows that he will have to present his product to other professionals? Additionally, such a presentation might disclose some bugs which are otherwise hard to find, resulting in a strong psychological influence on the programmer. He will automatically write programs which are simpler to read, better structured, and easier to maintain. During such a presentation the internal structure of a program is being disclosed with the main goal to detect faults. Therefore such a procedure is in general called a ``White Box Test'' .
In addition to those tests done in teams, some other white box tests have been derived from one of the oldest tests -- the desk-test -- a programmer checking his work at his desk . In the following some of the most common white box tests out of both fields will be shown.