Python Programming Essentials - M39 - Unit Testing

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Unit Testing
Pavan Verma
@YinYangPavan
Founder, P3 InfoTech Solutions Pvt. Ltd.
Python Programming Essentials

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What is Unit Testing
 A software testing method by which individual
units of source code are tested to determine if
they are fit for use.
 Unit testing is a software development
process in which the smallest testable parts of
an application, called units, are individually
and independently scrutinized for proper
operation. Unit testing is often automated but
it can also be done manually.

Unit Testing Glossary
 test fixture – A test fixture represents the
preparation needed to perform one or more
tests, and any associate cleanup actions. This
may involve, for example, creating temporary or
proxy databases, directories, or starting a server
process.

Unit Testing Glossary (2)
 test case – A test case is the smallest unit
of testing. It checks for a specific response
to a particular set of inputs.
 Python unittest module provides a base
class, TestCase, which may be used to
create new test cases.

 test suite – A test suite is a collection of
test cases, test suites, or both. It is used to
aggregate tests that should be executed
together.

 test runner – A test runner is a component
which orchestrates the execution of tests
and provides the outcome to the user.
 The runner may use a graphical interface,
a textual interface, or return a special value
to indicate the results of executing the
tests.

Unittest module
 The unittest module started life as the
third-party module PyUnit.
 PyUnit was a Python port of JUnit, the
Java unit testing framework.

Program to test – primes.py
def is_prime(number):
"""Return True if *number* is prime.""“
for element in range(number):
if number % element == 0:
return False
return True

Basic unit test example
import unittest
from primes import is_prime
class PrimesTestCase(unittest.TestCase):
"""Tests for `primes.py`.""“
def test_is_five_prime(self):
"""Is five successfully determined to be
prime?""“
self.assertTrue(is_prime(5))
if __name__ == '__main__':
unittest.main()

Running a unit test
$ python test_primes.py
E ======================================================================
ERROR: test_is_five_prime (__main__.PrimesTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "test_primes.py", line 8, in test_is_five_prime
self.assertTrue(is_prime(5))
File "/home/jknupp/code/github_code/blug_private/primes.py", line 4, in
is_prime
if number % element == 0:
ZeroDivisionError: integer division or modulo by zero
----------------------------------------------------------------------
Ran 1 test in 0.000s

Assertions
Method Checks that
assertEqual(a, b) a == b
assertNotEqual(a, b) a != b
assertTrue(x) bool(x) is True
assertFalse(x) bool(x) is False
assertIs(a, b) a is b
assertIsNot(a, b) a is not b
assertIsNone(x) x is None
assertIsNotNone(x) x is not None
assertIn(a, b) a in b
assertNotIn(a, b) a not in b
assertIsInstance(a, b) isinstance(a, b)
assertNotIsInstance(a, b) not isinstance(a, b)

Assertions (2)
Method Checks that
assertAlmostEqual(a, b) round(a-b, 7) == 0
assertNotAlmostEqual(a, b) round(a-b, 7) != 0
assertGreater(a, b) a > b
assertGreaterEqual(a, b) a >= b
assertLess(a, b) a < b
assertLessEqual(a, b) a <= b
assertRegexpMatches(s, r) r.search(s)
assertNotRegexpMatches(s, r) not r.search(s)
assertItemsEqual(a, b)
sorted(a) == sorted(b) and works with
unhashable objs
assertDictContainsSubset(a, b) all the key/value pairs in a exist in b

setUp and tearDown
#!/usr/bin/python
import unittest
class FooTest(unittest.TestCase):
"""Sample test case"""
# preparing to test
def setUp(self):
""" Setting up for the test """
print "FooTest:setUp_:begin"
## do something...
print "FooTest:setUp_:end"
# ending the test

setUp and tearDown (2)
def tearDown(self):
"""Cleaning up after the test"""
print "FooTest:tearDown_:begin" ## do
something...
print "FooTest:tearDown_:end" # test routine A
def testA(self):
"""Test routine A"""
print "FooTest:testA"
# test routine B
def testB(self):
"""Test routine B"""
print "FooTest:testB"

setUp and tearDown (3)

Unittest features
 setupClass() / tearDownClass()
 Skip tests
 Expected failures

Testing Frameworks
 pytest
 Nose

Code coverage
 coverage
http://nedbatchelder.com/code/coverage/

References
 https://docs.python.org/2/library/unittest.ht
ml
 http://pytest.org/
 http://nose.readthedocs.org/
 http://nedbatchelder.com/code/coverage/

Python Programming Essentials - M39 - Unit Testing

Python Programming Essentials - M39 - Unit Testing

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