When should I use Debug.Assert()?

Question

I\'ve been a professional software engineer for about a year now, having graduated with a CS degree. I\'ve known about assertions for a while in C++ and C, but had no idea t

Answer 1

Quote Taken from The Pragmatic Programmer: From Journeyman to Master

Leave Assertions Turned On

There is a common misunderstanding about assertions, promulgated by the people who write compilers and language environments. It goes something like this:

Assertions add some overhead to code. Because they check for things that should never happen, they'll get triggered only by a bug in the code. Once the code has been tested and shipped, they are no longer needed, and should be turned off to make the code run faster. Assertions are a debugging facility.

There are two patently wrong assumptions here. First, they assume that testing finds all the bugs. In reality, for any complex program you are unlikely to test even a miniscule percentage of the permutations your code will be put through (see Ruthless Testing).

Second, the optimists are forgetting that your program runs in a dangerous world. During testing, rats probably won't gnaw through a communications cable, someone playing a game won't exhaust memory, and log files won't fill the hard drive. These things might happen when your program runs in a production environment. Your first line of defense is checking for any possible error, and your second is using assertions to try to detect those you've missed.

Turning off assertions when you deliver a program to production is like crossing a high wire without a net because you once made it across in practice. There's dramatic value, but it's hard to get life insurance.

Even if you do have performance issues, turn off only those assertions that really hit you.