[Pyunit-interest] Avoiding side-effects in differnet tests

[Jason S. <jh...@oe...>]

Hi.  I started using pyunit, and I ran into a worrisome problem.  A 
side-effect had occured from a previous test (the module function 
acquired a threading.Lock, then raised an exception without releasing). 
  That is causing a problem in a later test.  Until now, I had assumed 
that each unit test was operating in a clean environment.  Maybe some 
code will help:

class ATest(unittest.TestCase):
	def testA(self):
		"""This test will cause a side-effect"""
		import myBuggyModule
		assert myBuggyModule.functionWithSideEffect()
	def testB(self):
		"""This test will fail becaus of testA"""
		import myBuggyModule
		assert myBuggyModule.someOtherFunction()

What I had assumed is that by putting the "import myBuggyModule" 
statement in each test, it would get re-evaluated.  But now it looks 
like that is not the case, and Python uses a previously-evaluated module 
  and just imports it into the test method's namespace.

This feels wrong to me, because each test case should run in a pristine 
environment.  That is especially so since the purpose of test cases is 
to cause problems and detect exceptions.  I think if certain module 
globals need to be set, they should be set in the test case, or in the 
setUp() method.

Any comments or advice are appreciated.  Thanks much.

-- 
Jason Smith
Open Enterprise Systems
Bangkok, Thailand
http://oes.co.th