setUp and tearDown

Date: January 17th 2016
Last updated: January 17th 2016

setUp and tearDown methods are used to isolate processes not being tested. In addition, setUp and tearDown methods allow multiple test functions to be re-factored.

Assuming the previous file structure:

Project
├── test
│   ├── __init__.py
│   ├── sentence.txt                # add test file 
│   ├── test_setup_teardown.py      # copy of unittest test_vowels
│   ├── test_vowels_nose.py
│   └── test_vowels.py
└── vowels
    ├── __init__.py
    ├── vowelsclass.py
    └── vowels.py

Add sentence.txt to test directory:

This is a test.
The is the second line of testing.
And the third... etc etc

Copy and modify the unittest function to test_setup_teardown.py

#!bin/python2.7
# teset_setup_teardown.py
"""
This module tests setup and teardown methods. 
Test function writen using unittest module.
"""
import unittest
from vowels import vowels

class VowelsTest(unittest.TestCase):
    # setUp gets processed first
    # open up the required file
    def setUp(self):
        print "<--- opening file --->"
        self.file = open("test/sentence.txt", "r")
        # get the first line
        self.lines = self.file.readline()
        # Returns: 'This is a test.\n'        
        # more processing can happen in here too...
        self.sentence = self.lines.split('\n')[0]
        # Returns: 'This is a test.'

    # tearDown gets processed last
    # close the text file
    def tearDown(self):
        print "<--- closing file --->"
        self.file.close()

    # functions process in the middle between setUp and tearDown
    # same function as before: slightly modified

    def testNormalCase(self):
        # replace "this is a test" to self.sentence
        self.assertEqual(vowels.count_vowels(self.sentence), 4)
        #self.assertEqual(vowels.count_vowels('this is a test'), 4)

if __name__ == '__main__':
    unittest.main()

Run with any test module:

# Run from Project folder
cd Project
# unittest
python -m unittest test.test_setup_teardown
# nose
nosetests -vv test/test_setup_teardown.py
# pytest
py.test -vv -s test/test_setup_teardown.py

Output from pytest: