Do you use assertions? [closed]

Answer 1

No, I don't use them.

I was taught, that asserts should not be used in 'production' code, and before I start using something that I have to remove anyway - according to what I've learned - I stick with exception to validate conditions.

Answer 2

I was taught to use lots of assertions back in the 90s and they made great sense. It's good defensive coding.

However, I think this has now been superceded by unit testing that actually forces the code to run and tells where it is broken. Debug asserts required someone to actually be running debug code and looking at the ui or logs. Unit testing can automate this.

Answer 3

I use assertions to make sure that I don't introduce errors in my code. If I know that a value should be in a map, I assert for that (using the assert keyword). If I know that a parameter should never be null, I assert for that. If I know that the parameter can be null, then I will check it and throw the appropriate exception.

I read it at Code Complete or Effective Java - assertions should be used to detect programming errors - exceptions should be used to handle exceptional but possible situations. You don't need to check for null on every method on your code if you know that the value will not be null (as defined by a contract), but it doesn't hurt to assert if a value is not null. Assertions are only enabled if you specify the parameter -ea to the VM and they should not impact the performance of your application if disabled.

You should use more logging too :-). Learn when to use trace, debug and info and make sure that you log everything that your application does. It makes life so easier when you have to figure out why something is not working in a production environment.

Answer 4

I don't use them. Unit tests should be sufficient to test your code. Furthermore, since they're disabled by default, they're normally completely ignored anyways. Then they just tend to clutter up your code with useless assertions that could be better expressed as comments.

If you really need this, though, some libraries have assertion static methods you can call that will not be skipped - these are also a lot more readable, because the assert keyword is uncommon and immediately may cause a "wtf" moment, but the Assert.x methods are just methods that can be traced through. The Spring framework, in particular, uses an assertion library.