unit-testing-training

This repo provides a Python module (functions.py) and a corresponding module (functions_test.py) containing unit tests for functions.py.

Setup

After cloning this repo:

git clone git@github.com:optimizely/unit-testing-training.git

cd unit-testing-training

... run the shell script to install dependencies and create a virtualenv (this will ask for your system password):

./setup.sh

Then enter your new virtualenv:

source .virtualenv/bin/activate

And finally run all the Python tests in this repo:

python -m unittest discover

Where To Start

Try breaking one of the tests and rerunning the tests. In functions.py, change:

def add_three_to_value(value):
  return value + 3

to

def add_three_to_value(value):
  return value + 4

Then once again run:

python -m unittest discover

And you should see something like:

======================================================================
FAIL: test_add_three_to_value__with_seven (test_my_functions.MyFunctionsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/username/repos/unit-testing-training/test_my_functions.py", line 15, in test_add_three_to_value__with_seven
    self.assertEqual(10, my_functions.add_three_to_value(7))
AssertionError: 10 != 11

======================================================================
FAIL: test_add_three_to_value__with_ten (test_my_functions.MyFunctionsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/username/repos/unit-testing-training/test_my_functions.py", line 18, in test_add_three_to_value__with_ten
    self.assertEqual(13, my_functions.add_three_to_value(10))
AssertionError: 13 != 14

----------------------------------------------------------------------
Ran 6 tests in 0.002s

FAILED (failures=2)

Hopefully that helps makes the setup a bit more concrete. Fiddle freely with the tests!

More Reading/Viewing

• Rambling presentation on unit testing using this repo: https://drive.google.com/a/optimizely.com/file/d/0B3DMe9ZATniSWnZqdHdFQ3J1T0E/view?usp=sharing
• https://docs.python.org/2/library/unittest.html
• https://docs.python.org/3/library/unittest.mock.html
• https://www.toptal.com/python/an-introduction-to-mocking-in-python