Checking correctness (a first step towards testing)

This lesson covers writing a simple test in Julia, with the aim of taking the first step towards checking your program is correct.

You learn the basic idea of test code: confirming with an if statement whether a condition came out as expected. Checking automatically that a function's result is right saves you doing it by hand every time.

The sample code checks with an if statement whether add(2, 3) gives 5, printing a pass or a fail accordingly. It gives you a feel for confirming a result in code rather than by eye.

A common early stumble is checking behaviour by hand every time and missing something. In practice you would use the standard Test module, but the underlying idea is the same.

Remember too that an assertion is a development-time debugging aid, not a substitute for real error handling in production.