bug in python documentation?

Sat Sep 11 11:34:35 EDT 2010

from http://docs.python.org/library/unittest.html
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Here is a short script to test three functions from the random module:
import random
import unittest
class TestSequenceFunctions(unittest.TestCase):
 def setUp(self):
 self.seq = range(10)
 def test_shuffle(self):
 # make sure the shuffled sequence does not lose any elements
 random.shuffle(self.seq)
 self.seq.sort()
 self.assertEqual(self.seq, range(10))
 # should raise an exception for an immutable sequence
 self.assertRaises(TypeError, random.shuffle, (1,2,3))
 def test_choice(self):
 element = random.choice(self.seq)
 self.assertTrue(element in self.seq)
 def test_sample(self):
 with self.assertRaises(ValueError):
 random.sample(self.seq, 20)
 for element in random.sample(self.seq, 5):
 self.assertTrue(element in self.seq)
if __name__ == '__main__':
 unittest.main()
--8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<--
but test_sample() it's a strange method: what's that "with 
self.assertRaises(ValueErrorr)"?
infact, running the script I have
$ python test_unittest.py
.E.
======================================================================
ERROR: test_sample (__main__.TestSequenceFunctions)
----------------------------------------------------------------------
Traceback (most recent call last):
 File "./test_data_manip.py", line 23, in test_sample
 with self.assertRaises(ValueError):
TypeError: failUnlessRaises() takes at least 3 arguments (2 given)
----------------------------------------------------------------------
Ran 3 tests in 0.001s
FAILED (errors=1)
$
-- 
By ZeD