15. Some Thoughts about Testing

15 Some Thoughts about Testing

15.1 Goals

It is not possible to prove that a program is correct by testing. On the contrary, it has been formally proven that it is impossible to prove programs in general by testing. Theoretical program proofs or plain examination of code can be viable options for those wishing to certify that a program is correct. The test server, as it is based on testing, cannot be used for certification. Its intended use is instead to (cost effectively) find bugs. A successful test suite is one that reveals a bug. If a test suite results in OK, then we know very little that we did not know before.

15.2 What to Test

There are many kinds of test suites. Some concentrate on calling every function or command (in the documented way) in a certain interface. Some others do the same, but use all kinds of illegal parameters, and verify that the server stays alive and rejects the r