python-dectest — Improved unittest.TestCase

I have released the first version of dectest for Python (Github), an improved version of unittest.TestCase. It is a drop-in replacement with two improvements:

  • decorators for tests, setup, and teardown methods. This is not only more explicit than the “magic” names of unittest, it also allows multiple setup and teardown methods per class.
  • patch() helper method that calls unittest.mock.patch(), but stops the patch during teardown.

New Python unittest module?

Collin Winter blogs about an updated unittest module he wrote. His update fixes the internal structure, and therefore the expandability, of the module, but also cleans up the external API. There are still a few minor improvements I would like to see, but nevertheless I hope that his updated version will be included in Python’s standard library eventually.

PyUnit and Decorators

One of the shortcomings of the Python standard library is in my opinion that PyUnit doesn’t use decorators (as later versions of JUnit and NUnit do). Therefore I have written a sample implementation that adds decorator support. (unittest.pydiff to Python 2.5’s unittest.py)

To do:

  • Warn when old-style and new-style tests are mixed.
  • Throw an exception when multiple setup or teardown methods exist.
  • Ability to warn when old-style methods are used.

XML Test Runner for PyUnit

JUnit features an XML Test Runner. This means that the result of a test run is not written to stdout, but instead written into an XML file. This XML file can then be automatically processed. This is for example useful for fully automated builds using software like CruiseControl. The XML output is easily converted into an XHTML file for easy human reading.

Until now PyUnit was lacking an XML Test Runner. Since I needed one for one of my projects that used CruiseControl, I wrote one. It is available for download here. Since this is an extension to a unit testing framework, the classes are of course fully tested. 🙂

If you have any suggestions or criticism, please let me know. I’m a nitpicker myself, so even if you have some small suggestions about coding style or improvement hints, I would like to hear about them.

Update: I have now submitted this patch to Python’s patch tracker, ticket number 1522704.

Update^2: I created a page with more information about PyUnit and CruiseControl integration, including sample configuration files and scripts.

Update^3: I updated the XmlTestRunner after input from Mirko Friedenhagen: It now recovers gracefully from unit tests overriding sys.stdout and sys.stderr, the XmlTestRunner returns the TestResult instance instead of a boolean value, and you can now stream multiple test suite results into a single XML file, since the XML header is not written to file streams by default.

Update 2017-10-30: While XMLTestRunner can be found on GitHub nowadays, its use has been deprecated for a while. Instead, use maintainer projects, such as unittest-xml-reporting.

Python Warts

I started my own page of Python warts, similar to A. M. Kuchling’s popular page. At the moment it just features one wart (the len() function vs. a length property on container classes). But I plan to add more warts in the future. I will probably concentrate on warts in the standard library. (And there are tons of them.) Two warts that come to mind are the unpythonic (but very SAXy) SAX library, and several warts in the unittest module.