dynamic unittest

[Oleg Paraschenko]

Hello,

I decided to re-use functionality of "unittest" module for my purposes.
More precisely, I have a list of folders. For each folder, code should
enter to the folder, execute a command and assert the output. It's
reasonable to use "unittest" here, but the problem is that "unittest"
doesn't support (== I haven't found how) dynamic creation of tests.

I thought it would be very easy, but due to lack of closures in Python
(more precisely, closures do exist, but they are counter-intuitive for
lisp programmers), I failed. Finally, I found a way using a global
variable. I exploit the fact that "unittest" uses "cmp" to arrange test
cases. Therefore, if we have an array of test names and sequential
number of running the common function, we know the name of the current
test. Here is a sample code:

------- <dynamic_unittest.py>

import sys, unittest
test_names = ['aaa', 'ddd', 'bbb']
test_names.sort()
test_index = 0

class DynamicTestCase(unittest.TestCase):
def one_test(self):
global test_index
test_name = test_names[test_index]
test_index = test_index + 1
# Ok for 'aaa' and 'bbb', failure for 'ddd'
assert test_name in ['aaa', 'bbb']

for test_name in test_names:
func_name = 'test_' + test_name
setattr(DynamicTestCase, func_name, DynamicTestCase.one_test)

suite = unittest.makeSuite(DynamicTestCase, 'test_')
if not unittest.TextTestRunner().run(suite).wasSuccessful():
sys.exit(1)

------- </dynamic_unittest.py>

I think this code might help others, so I post it to the group.
Comments are welcome.

 

[Peter Otten]

Hello,

I decided to re-use functionality of "unittest" module for my purposes.
More precisely, I have a list of folders. For each folder, code should
enter to the folder, execute a command and assert the output. It's
reasonable to use "unittest" here, but the problem is that "unittest"
doesn't support (== I haven't found how) dynamic creation of tests.

I thought it would be very easy, but due to lack of closures in Python
(more precisely, closures do exist, but they are counter-intuitive for
lisp programmers), I failed. Finally, I found a way using a global
variable. I exploit the fact that "unittest" uses "cmp" to arrange test
cases. Therefore, if we have an array of test names and sequential
number of running the common function, we know the name of the current
test. Here is a sample code:

------- <dynamic_unittest.py>

import sys, unittest
test_names = ['aaa', 'ddd', 'bbb']
test_names.sort()
test_index = 0

class DynamicTestCase(unittest.TestCase):
def one_test(self):
global test_index
test_name = test_names[test_index]
test_index = test_index + 1
# Ok for 'aaa' and 'bbb', failure for 'ddd'
assert test_name in ['aaa', 'bbb']

for test_name in test_names:
func_name = 'test_' + test_name
setattr(DynamicTestCase, func_name, DynamicTestCase.one_test)

suite = unittest.makeSuite(DynamicTestCase, 'test_')
if not unittest.TextTestRunner().run(suite).wasSuccessful():
sys.exit(1)

------- </dynamic_unittest.py>

I think this code might help others, so I post it to the group.
Comments are welcome.

Here's what your code might look like with closures:

import sys
import unittest

test_names = ['aaa', 'ddd', 'bbb']
test_names.sort()

class DynamicTestCase(unittest.TestCase):
pass

def make_test(test_name):
def one_test(self):
self.assert_(test_name in ['aaa', 'bbb'])
return one_test

for test_name in test_names:
setattr(DynamicTestCase, 'test_' + test_name, make_test(test_name))

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

Peter

 

[Oleg Paraschenko]

Hello Peter,

thanks a lot. I've overlooked this simple way to create the right
closure.