bug in python documentation?

[Vito 'ZeD' De Tullio]

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