changeset:   104485:d4e715e725ef
branch:      3.6
parent:      104482:beed43d7dc46
user:        Raymond Hettinger <python@rcn.com>
date:        Fri Oct 14 01:19:38 2016 -0400
files:       Lib/test/test_random.py
description:
Issue #18844:  Add more tests


diff -r beed43d7dc46 -r d4e715e725ef Lib/test/test_random.py
--- a/Lib/test/test_random.py	Thu Oct 13 14:32:33 2016 -0700
+++ b/Lib/test/test_random.py	Fri Oct 14 01:19:38 2016 -0400
@@ -205,6 +205,20 @@
         ]:
             self.assertTrue(set(choices(data, cum_weights=weights, k=5)) <= set(data))
 
+        # Test weight focused on a single element of the population
+        self.assertEqual(choices('abcd', [1, 0, 0, 0]), ['a'])
+        self.assertEqual(choices('abcd', [0, 1, 0, 0]), ['b'])
+        self.assertEqual(choices('abcd', [0, 0, 1, 0]), ['c'])
+        self.assertEqual(choices('abcd', [0, 0, 0, 1]), ['d'])
+
+        # Test consistency with random.choice() for empty population
+        with self.assertRaises(IndexError):
+            choices([], k=1)
+        with self.assertRaises(IndexError):
+            choices([], weights=[], k=1)
+        with self.assertRaises(IndexError):
+            choices([], cum_weights=[], k=5)
+
     def test_gauss(self):
         # Ensure that the seed() method initializes all the hidden state.  In
         # particular, through 2.2.1 it failed to reset a piece of state used