I don't use the Test::* modules as they tell me what passed rather than what failed. I also have very definite ideas about the form that unit testing should take and that does not fit well with the pattern of a zillion ok()/not_ok() tests that those modules encourage.
I've been in a QA a position for only a few months (though I've been coding Perl for years) and am intersted in new perspectives on testing software. Would you care to tell me what modules you do use in testing and expand more on your perspective on testing?
--DrWhy
"If God had meant for us to think for ourselves he would have given us brains. Oh, wait..."
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See Test::LectroTest for the only cpan test module (I consider) worthy of the Test:: prefix.
Simplified rational:
Most bug arise as a result of the programmer making assumptions. If the same programmer writes the tests for the code s/he wrote, they will make the same assumptions. The net result is they write tests for every case they considered when writing the code, which all pass--giving them N of N tests (100%) passed and a hugely false sense of security.
The cases they fail to tests for, are the same cases they failed to consider when writing the code, and those are normally the same cases that crop up immediately they demo it or put it into production.
With anything other than the most trivial of functions, hoping to test all possible combinations of inputs and verify those outputs is forlorn. Ie. impossible for any practical sense of the term.
Therefore, the only way to test code is to test is complience against a (rigourous) specification, and derive security through statistics. Ideally, this would go one step further than LectroTest and retain a record of failing values and these would be reused (along with a new batch of randomly generated ones) at each subsequent test cycle. (IMO) this is the only way that testing will be lifted out of it's finger-to-the-wind, guesswork state and move into something approaching a science.
LectroTest isn't perfect (yet). It has fallen into the trap of becoming "expectation complient" in as much as it plays the Test::Harness game of supplying lots of warm-fuzzies in the form of ok()s, and perpectuating the anomoly of reporting 99.73% passed instead of 0.27 "failed", or better still:
***FAIL*** Line nnn of xxxxxx.pl failed running
function( 1, 2, 3 );
Testing halted.
Preferably dropping the programmer into the debugger at the point of failure. Even more preferably, in such a way that the program can be back-stepped to the point of invocation and single stepped through the code with the failing parameters in-place so that the failure can be followed.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
"Science is about questioning the status quo. Questioning authority".
The "good enough" maybe good enough for the now, and perfection maybe unobtainable, but that should not preclude us from striving for perfection, when time, circumstance or desire allow.
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Most bug arise as a result of the programmer making assumptions. If the same programmer writes the tests for the code s/he wrote, they will make the same assumptions. The net result is they write tests for every case they considered when writing the code, which all pass--giving them N of N tests (100%) passed and a hugely false sense of security.
I find that this does not happen if you're using TDD. When you only write code by producing a failing test you are forced to challenge the assumptions in your code at every stage. Every time you make something work the next stage is "how do I break this".
Therefore, the only way to test code is to test is complience against a (rigourous) specification, and derive security through statistics.
As you can probably guess I don't agree with with the "therefore" and "only" :-)
Specification based testing is a great tool, but it's certainly not the be-all and end-all of testing. It brings it's own set of good and bad points to the table, and is still affected by bad developer assumptions about the code. They're just assumptions of a different kind.
There's a whole bunch of different ways to go about testing. From specification based tests like Test::LectroTest, xUnit frameworks like Test::Class, procedural tests like the basic uses of Test::More and friends, data driven tests like Test::Base, exploratory testing, integration testing frameworks like FIT, etc.
Take a look at Lessons Learned in Software Testing for a great book on the multitude of useful approaches to testing.
Not to mention practices like Test Driven Development and Design By Contract.
Picking the best tool for the work at hand is part of job.
LectroTest isn't perfect (yet). It has fallen into the trap of becoming "expectation complient" in as much as it plays the Test::Harness game of supplying lots of warm-fuzzies in the form of ok()s, and perpectuating the anomoly of reporting 99.73% passed instead of 0.27 "failed", or better still:
Well the nice thing about Perl is that if you don't like the test reporting you can always change it. In fact, since I spent a chunk of yesterday re-learning how to fiddle with Test::Harness::Straps...
.... insert sound of typing here ...
...there you go.
Personally, since test suites in Perl take so darn long to run, I like seeing the okays whirl past in the background since it let's me know the darn thing hasn't hung.
I realise that anything less than 100% pass at the end means I've fucked up, warm-fuzzies or not.
Preferably dropping the programmer into the debugger at the point of failure. Even more preferably, in such a way that the program can be back-stepped to the point of invocation and single stepped through the code with the failing parameters in-place so that the failure can be followed.
There are already so called Omniscient Debugging tools available for Java. So I guess it's just a trivial matter of programming :-)
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