ciforth is one of the few Forth I know, that fulfills professional demands with respect to testing. The testing is simple, in principle. The work consists of exhaustive tests for each Forth word. We use so called redirection, which means that we take care that the program gets it input from a file instead of the keyboard. This uses the symbols '<' en '>' . It amounts to saying that invoer.frt consists of all tests that we could have typed manually in principle. After

ciforth < invoer.frt > uitvoer

the file uitvoer contains everything that would otherwise have appeared on the screen. The file uitvoer is now compared to the expected output that is also generated automatically. If there are no difference, everything is all right. This is called a regression test, if it is run diligently after every change. Redirection works for MSDOS, Linux and Windows.