Earlier test for zero total weight

python · rhettinger · May 8, 2020 · May 6, 2020 · May 6, 2020 · May 6, 2020
commit 556582d25bacb12b5a7c013a898679a51d88c625
diff --git a/Lib/random.py b/Lib/random.py
@@ -391,7 +391,7 @@ def sample(self, population, k, *, weights=None):
            total = cum_weights.pop()
            if not isinstance(total, int):
                raise TypeError('Weights must be integers')
-            if total < 0:
+            if total <= 0:
                raise ValueError('Total of weights must be greater than zero')
            selections = sample(range(total), k=k)
            bisect = _bisect

diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py
@@ -196,6 +196,8 @@ def test_sample_with_weights(self):
            sample(['red', 'green', 'blue'], weights=10, k=10)               # weights not iterable
        with self.assertRaises(ValueError):
            sample(['red', 'green', 'blue'], weights=[-3, -7, -8], k=2)      # weights are negative
+        with self.assertRaises(ValueError):
+            sample(['red', 'green', 'blue'], weights=[0, 0, 0], k=2)         # weights are zero
        with self.assertRaises(ValueError):
            sample(['red', 'green'], weights=[10, 10], k=21)                 # population too small
        with self.assertRaises(ValueError):