Video - http://www.youtube.com/watch?v=DTNejE9EraI Code - https://gist.github.com/3386951 Pytest is a mature and comprehensive testing suite for Python projects, but it can be a little intimidating for newcomers. Where do these mysterious funcargs come from, how do parametrised tests work, and where are my xUnit-style setUp and tearDown methods? Pytest lives by "convention over configuration" - which is great once you know what the conventions are. This talk will look at real examples of pytest in use, emphasising the features that differentiate it from nose.

1. funcargs &
other fun
with
pytest
PyCon AU 2012
Brianna Laugher

2. pytest – all the good stuff
✔
all test styles: unittest, doctest, nose
✔
boilerplate-free style – natural asserts
✔
support for running tests distributed, boxed
✔
generate JUnit-style XML for Jenkins CI
✔
informative error reporting
✔
extensible plugins, useful builtins
✔
skip, xfail, custom markers
✔
parametrize, generate tests
✔
monkeypatch
✔
funcargs!

4. my background
●
using pytest seriously for ~18 months at work
●
really enjoying it!
●
how it feels to use pytest: →

8. Graphical Forecast Editor
●
client/server desktop application used by
forecasters to generate the (text & graphical)
forecasts
●
pilot in VIC, funding to roll out nationally, ~5
year project, 20+ new devs/testers
●
existing codebase of Python and C++ (used
operationally in US)
●
home-grown test suite and runner (via GUI)

10. informative error reporting

11. informative error reporting

12. extensible
●
e.g. add in unittest assert methods

13. extensible
●
e.g. add hook for winpdb

15. skip

16. xfail

17. custom markers

19. parametrize

21. generate tests
●
defined once per module
●
list/generate data to supply to 1+ tests
●
way more flexible cf. py.test.mark.parametrize

22. generate generators!

24. monkeypatch

29. funcargs!

30. funcargs – idealised db example

31. funcargs – trivial django example

32. funcargs – trivial GAE examples

33. funcargs – trivial GAE examples

35. funcargs – why?
●
dependency injection, aka inversion of control
●
works a treat with TDD
●
very natural with mocking
●
encourages modular design

37. funcargs – a real DB example

38. funcargs – a real DB example

39. funcargs – to express prereq's
●
for when a decorator is not powerful enough

41. funcargs – to hide monkeypatch :)

43. generate + funcarg - anypython

46. pytest – the future

48. test evolution -v0

50. test evolution - v1

51. test evolution - v2

52. test evolution – v3

53. test evolution - v4

55. pytest – all the good stuff
✔
all test styles: unittest, doctest, nose
✔
boilerplate-free style – natural asserts
✔
support for running tests distributed, boxed
✔
generate JUnit-style XML for Jenkins CI
✔
informative error reporting
✔
extensible plugins, useful builtins
✔
skip, xfail, custom markers
✔
parametrize, generate tests
✔
monkeypatch
✔
funcargs!

58. ●
http://codespeak.net/mailman/listinfo/py-dev
●
testing-in-python mailing list
●
Stack Overflow
●
lead developer Holger Krekel is very
responsive

59. pytest.org

60. credits, thanks, contact
Comic panels from comicallyvintage.tumblr.com
Bureau of Meteorology
●
In particular, Darius Powell introduced pytest to our
project
Code examples: gist.github.com/3386951
brianna@modernthings.org
brianna.laugher.id.au / b.laugher@bom.gov.au
@pfctdayelise