diff options
| -rw-r--r-- | Lib/random.py | 6 | ||||
| -rw-r--r-- | Lib/test/test_random.py | 7 |
2 files changed, 12 insertions, 1 deletions
diff --git a/Lib/random.py b/Lib/random.py index 88b8f6d..0886562 100644 --- a/Lib/random.py +++ b/Lib/random.py @@ -239,7 +239,11 @@ class Random(_random.Random): def choice(self, seq): """Choose a random element from a non-empty sequence.""" - return seq[self._randbelow(len(seq))] # raises IndexError if seq is empty + try: + i = self._randbelow(len(seq)) + except ValueError: + raise IndexError('Cannot choose from an empty sequence') + return seq[i] def shuffle(self, x, random=None, int=int): """x, random=random.random -> shuffle list x in place; return None. diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py index f5c0030..08edead 100644 --- a/Lib/test/test_random.py +++ b/Lib/test/test_random.py @@ -42,6 +42,13 @@ class TestBasicOps(unittest.TestCase): self.assertRaises(TypeError, self.gen.seed, 1, 2, 3, 4) self.assertRaises(TypeError, type(self.gen), []) + def test_choice(self): + choice = self.gen.choice + with self.assertRaises(IndexError): + choice([]) + self.assertEqual(choice([50]), 50) + self.assertIn(choice([25, 75]), [25, 75]) + def test_sample(self): # For the entire allowable range of 0 <= k <= N, validate that # the sample is of the correct length and contains only unique items |