This document discusses unit testing in Python using the nose testing framework. It covers installing nose, writing different types of tests (functions, classes, generators), specifying test options, using fixtures, handling exceptions, setting timeouts, and configuring nose with files. The document recommends also trying the pytest framework and discusses philosophies around testing, such as testing only what provides value and tests becoming assertions. It concludes with an exercise to test date quarter calculation.

1. UNIT TESTING WITH
NOSE
César Cárdenas Desales

2. Installing nose
• Install pip
• Install virtualenv
• Install pip on your virtual environment
• http://bit.ly/1kCeZv8
$ wget https://bootstrap.pypa.io/get-pip.py
$ python get-pip.py
$ pip install virtualenv
$ virtualenv testingenv
$ source testingenv/bin/activate
$ python get-pip.py
$ pip install nose

3. Step 1: Freedom, no unittest boilerplate
$ nosetests
$ nosetests basic_tests.py
$ nosetests basic_tests

4. Step 2: Test functions
$ nosetests
$ nosetests basic_tests
$ nosetests basic_tests:test_sum
$ nosetests basic_tests:test_failing_sum

5. Step 3: Test classes
$ nosetests basic_tests:TestSuite
$ nosetests basic_tests:TestSuite.test_mult
$ nosetests basic_tests:TestSuite.ignored

6. Step 4: Specify tests
$ nosetests --collect-only -v
$ nosetests --collect-only -v -s
$ nosetests -v -s
$ nosetests -v --nocapture

7. Step 5: Config files
$ nosetests -v -c config.ini

8. Step 6: Fixtures
=> @with_setup(setup_function, teardown_function)
$ nosetests –v

9. Step 7: Test generators & parallel testing
1 2 3 4 5
OK OK OK FAIL OK
$ nosetests -v
$ nosetests --processes=6

10. Step 8: Exceptions
$ nosetests –v

11. Step 9: Timeouts
$ nosetests -v basic_tests.py
$ nosetests -v --processes=6 --process-timeout=1 basic_tests2
Plugins! => --processes --no-capture –collect-only

12. Py.test anyone?
$ pip install pytest
$ py.test step1/basic_tests.py
$ py.test step2/basic_tests.py
$ py.test -v step4/basic_tests.py
...

13. Is TDD dead?
• No need to be purist and orthodox
• “I get paid for code that works, not for tests, so my philosophy is to
test as little as possible to reach a given level of confidence”
• – Kent Beck
• Test are code to maintain
• Test core algorithms, data structures, logic with Biz. Value
• Tests can become assertions
• Test give you confidence to do changes

14. Exercise
• Test whether the following code correctly calculates in
which quarter falls the provided datetime.date object

15. ¿?
• ¡ !