Re: [Pyunit-interest] comments on PyUnit

[Guido v. R. <gu...@di...>]

> At 12:26 PM 4/11/2001 -0500, Guido van Rossum wrote:
> >And that's exactly what I'm strongly opposing.  When "python -O" is
> >used, tests that use the assert statement will not be performed
> >correctly, because no code is compiled for assert statements in that
> >case.  It's a nasty trap to fall into, and the fact that the PyUnit
> >framework uses AssertionError makes it a common mistake.
> 
> But isn't this the real problem?
> 
> I had an advanced application a few years back in Objective-C, where GNU 
> optimizations and macro assertions were 2 separate deals. At one point, I 
> compiled with assertions off and tested the program. The gain in 
> performance was 0.5% so I decided to ship the product to customers with 
> optimization as well as assertions. Even if it had been 10%, I still would 
> have kept assertions.
> 
> The reason to keep assertions is that they raise exceptions which can then 
> be caught and dealt with appropriately, such as notifying customer support, 
> or skipping the processing of a troubled object within a larger set of objects.
> 
> The alternative is that the program keeps chugging through an erroneous 
> situation. It's doubtful that you covered that in your testing and that you 
> know what the results will be. What's even more doubtful is that anything 
> intelligent will happen past the point where the "missing assertion" was 
> located.
> 
> Also, it shouldn't be surprising that assertions don't slow software down 
> by much. Your algorithms and caching and such are what's most important. 
> Assertions pretty much ride along with your processing as extra 
> instructions, not necessarily extra complexity.
> 
> Finally, consider the flip side: Is there any reason to give to developers 
> that their assertions MUST be disabled for optimization?

I agree 100% with you, and we're planning to separate the assertions
from optimizations some time in the future.  Howver, since it will
still be possible to turn off assertions, it's still a bad idea to use
AssertionError as the exception blessed by PyUnit.

--Guido van Rossum (home page: http://www.python.org/~guido/)