Re: [Tutor] More on unit testing - tests for external data...
On Thu, Dec 10, 2009 at 11:19 PM, Modulok wrote: > It seems like there are a lot of people on this list interested in > getting more familiar with unit testing, but not a whole lot of > non-trivial, python-specific examples being passed around. > Case studies/tutorials anyone? Unit testing has become common, accepted practice in open source projects so real-world examples abound. Python itself has extensive unit tests. To a large extent they actually define the language and the libraries - Jython and IronPython use the CPython test suite to validate their implementations. Download the Python source to get a copy of the tests. The Python unit tests largely predate the unittest module so they are not necessarily good examples of unittest. I suggest you pick an open source Python project that you use or like and look at its test suite. Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] More on unit testing - tests for external data...
So, this, 'test environment', this is just like a directory where I place my code and associated files to test for the existence (and non-existence) of various stuff, right? Any real-world examples/case studies to point to? It seems like there are a lot of people on this list interested in getting more familiar with unit testing, but not a whole lot of non-trivial, python-specific examples being passed around. I can write a function in a programming 101 class that accepts two arguments and returns a value by computing the hypotenuse of a triangle (or whatever). I can then build a unit-test for that making sure it fails and passes as needed. Cake. But jump into the real-world where many things are not so trivial, and I'm at a loss for where this unit-testing business all fits in. Basically, I'm trying to become a better programmer. (Who isn't?) I'd like to transition from 'hacky but gets the job done' or 'oh my God it actually works' to 'eloquent and bulletproof'. Without some kind of a mentor or vast array of tutorials to lay down the law when I screw up, or pass on some kind of approval when I get something right - it's been frustrating as hell. Case studies/tutorials anyone? Thanks! -Modulok- On 12/10/09, spir wrote: > Wayne Werner dixit: > >> On Wed, Dec 9, 2009 at 6:15 PM, Alan Gauld >> wrote: >> >> > >> > Remember, in testing you are not trying to prove it works but rather to >> > demonstrate that it doesn't! >> > >> >> So in that way it's a bit like the the scientific method (or exactly >> like)? >> You create a hypothesis and design tests to invalidate your hypothesis... >> and if they fail to invalidate you may have a valid hypothesis. Simply >> replace hypothesis with program and you get the testing procedure? >> >> -Wayne >> >> > > programming is modelizing -- like a scientist's job > > Denis > > > la vita e estrany > > http://spir.wikidot.com/ > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] More on unit testing - tests for external data...
Wayne Werner dixit: > On Wed, Dec 9, 2009 at 6:15 PM, Alan Gauld wrote: > > > > > Remember, in testing you are not trying to prove it works but rather to > > demonstrate that it doesn't! > > > > So in that way it's a bit like the the scientific method (or exactly like)? > You create a hypothesis and design tests to invalidate your hypothesis... > and if they fail to invalidate you may have a valid hypothesis. Simply > replace hypothesis with program and you get the testing procedure? > > -Wayne > > programming is modelizing -- like a scientist's job Denis la vita e estrany http://spir.wikidot.com/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] More on unit testing - tests for external data...
On Thu, Dec 10, 2009 at 11:20 AM, Wayne Werner wrote: > On Wed, Dec 9, 2009 at 6:15 PM, Alan Gauld > wrote: >> >> Remember, in testing you are not trying to prove it works but rather to >> demonstrate that it doesn't! > > So in that way it's a bit like the the scientific method (or exactly like)? > You create a hypothesis and design tests to invalidate your hypothesis... > and if they fail to invalidate you may have a valid hypothesis. Simply > replace hypothesis with program and you get the testing procedure? > -Wayne Nice analogy! And like with a scientific hypothesis, you can never be sure your program is correct, only that all your attempts to prove it incorrect has failed. Kent ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] More on unit testing - tests for external data...
On Wed, Dec 9, 2009 at 6:15 PM, Alan Gauld wrote: > > Remember, in testing you are not trying to prove it works but rather to > demonstrate that it doesn't! > So in that way it's a bit like the the scientific method (or exactly like)? You create a hypothesis and design tests to invalidate your hypothesis... and if they fail to invalidate you may have a valid hypothesis. Simply replace hypothesis with program and you get the testing procedure? -Wayne -- To be considered stupid and to be told so is more painful than being called gluttonous, mendacious, violent, lascivious, lazy, cowardly: every weakness, every vice, has found its defenders, its rhetoric, its ennoblement and exaltation, but stupidity hasn’t. - Primo Levi ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] More on unit testing - tests for external data...
"Modulok" wrote Unit testing functions and methods which rely on passed data is simple enough. However: How do I unit test something which relies on external data? You have to build a test environment. This needs to be carefully planned to enable every test condition to be tested. For example, a function which creates a file only if it doesn't exist on disk, or a unit test for a function which makes an SQL query? So you would need a file that exists, one that doesn't(!), one that exists but is read-only, one that exists but wrong user ownership, and really a binary file and a text file and an empty file and a huge file too For the database it gets tricky, you need to create a database full of entries with all the possible scenarios you might encounter. For a large application with multiple joined tables designing such a test database can take a lot of time - but it is invaluable for testing and debugging and provided you store a clean copy somewhere before using it makes regression testing possible. Once you have the database you then need to write the test driver code that will provide the right keys for each test - database testing is one of the biggest challenges in system testing. And don't forget to test for behaviour with invalid user access on the database, and for locking and simultaneous updates etc. And if its on a separate server that you check behaviour when the server or network is down or running slowly (eg by lowering server priorioty and running a huge bulk update in the background). Remember, in testing you are not trying to prove it works but rather to demonstrate that it doesn't! -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] More on unit testing - tests for external data...
List, Unit testing functions and methods which rely on passed data is simple enough. However: How do I unit test something which relies on external data? For example, a function which creates a file only if it doesn't exist on disk, or a unit test for a function which makes an SQL query? If anyone could point to a few examples of such usage, that would be great! Thanks! -Modulok- ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
