alister wrote: > And as may wiser people than me have already highlighted Assertions can > be switched off in python which means they cannot be relied upon in > production code invalidating the authors suggestion that they can > automate bug reports & "Extend testing into the lifetime of the product"
I'm afraid that you appear to have missed the point of assertions as tests. Since they should never be used to *enforce* correct behaviour, but only to *verify* behaviour is correct (i.e. as a form of testing), it doesn't matter if you disable them. If I turn them off, all that happens is that the tests won't run *for me*. The software will still be just as correct, or just as buggy, regardless of the assertions. But not everyone will turn them off. Even if *everybody else* turns them off, you, the developer of the software, surely won't[1] since you're not an idiot. (Why write assertions only to never use them?) That means that whenever you run your software during the process of development, your assertions will run. In a complex, rich software application, you may not have unit tests for every possible path through the software. But if you put assertions at the intersections of paths (e.g. at the top of each loop, or the entry and exit of each function), then even if you don't have a unit test for a particular path, at least the assertions will be there to provide limited testing. In other words, correctly written assertions can provide simple but effective test coverage of 100% of your application. I stress that assertions aren't a replacement for unit testing, but they compliment unit testing: assertions can help cover code missed by your unit tests, and check that your unit tests are correct. If the user of your application disables assertions, they will be no worse off than if you didn't write those assertions at all. And if they enable assertions, then they get extended testing throughout the lifetime of the product *for free*. (Well, perhaps not *quite* for free, since assertions do have some performance cost. But very cheaply.) [1] Thanks to Python defaulting to __debug__ = True, the problem is getting people to remember to test their software with assertions disabled, not to get them to enable them. -- Steven -- https://mail.python.org/mailman/listinfo/python-list
