'If the specified modules have never been imported, and import
prevention is not requested, L{ensureNotImported} has no effect.'

def test_ensureWhenNotImportedDontPrevent(self):

    modules = {}
    self.patch(sys, 'modules', modules)
    ensureNotImported(['m1', 'm2'], 'A    message.')
    self.assertEqual(modules, {})
