[TIP] Mocking sys.exit() and replacing it back?
fuzzyman at voidspace.org.uk
Fri Aug 6 07:51:10 PDT 2010
On 06/08/2010 15:41, Jorge Vargas wrote:
> On Fri, Aug 6, 2010 at 5:32 AM, Jonathan Lange <jml at mumak.net
> <mailto:jml at mumak.net>> wrote:
> On Fri, Aug 6, 2010 at 4:34 AM, Jorge Vargas
> <jorge.vargas at gmail.com <mailto:jorge.vargas at gmail.com>> wrote:
> > Hello,
> > Doing this seems really simple. All we need is something like
> > def mock_exit(exit_status):
> > return exit_status
> > class RunCommand(TestCase):
> > def setUp(self):
> > #we setup a fake sys.exit() to allow tests to continue
> > sys.exit = mock_exit
> > However I have two questions.
> > 1- do I need a tearDown that will replace sys.exit with the original
> > function?
> > 2- if so which is the best way to do this? store it in
> self.orig_exit ?
> > Or the test collector is smart enough to know it has to wipe out and
> > reimport everything on each testcase ?
> > In case someone asks this is with unittest2.
> Better than tearDown:
> def patch(self, obj, name, value):
> current = getattr(obj, name)
> setattr(obj, name, value)
> self.addCleanup(setattr, obj, name, current)
> return current
> def setUp(self):
> self.patch(sys, 'exit', mock_exit)
> That way, the code in setUp reads much closer to what you actually
> Awesome. That looks like a great and clean solution. Thank you!
Another alternative (although Jonathan's is fine) using the mock module.
from mock import patch
def testMethod(self, mock_exit):
.... # code
the mock.patch decorator handles patching and unpatching for you and
passes the mock it creates into your test method. The mock has a whole
host of useful features - including the assert_called_with used in the
All the best,
> testing-in-python mailing list
> testing-in-python at lists.idyll.org
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