bug in python documentation?

[Vito 'ZeD' De Tullio]

from http://docs.python.org/library/unittest.html

-->8---->8---->8---->8---->8---->8---->8---->8---->8---->8---->8---->8--

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)