bpo-42944 Fix Random.sample when counts is not None (GH-24235) (GH-24243)

Author: miss-islington

Lib/random.py

@@ -442,7 +442,7 @@ def sample(self, population, k, *, counts=None):
                 raise TypeError('Counts must be integers')
             if total <= 0:
                 raise ValueError('Total of counts must be greater than zero')
-            selections = sample(range(total), k=k)
+            selections = self.sample(range(total), k=k)
             bisect = _bisect
             return [population[bisect(cum_counts, s)] for s in selections]
         randbelow = self._randbelow

Lib/test/test_random.py

@@ -207,33 +207,6 @@ def test_sample_with_counts(self):
         with self.assertRaises(ValueError):
             sample(['red', 'green', 'blue'], counts=[1, 2, 3, 4], k=2)      # too many counts
 
-    def test_sample_counts_equivalence(self):
-        # Test the documented strong equivalence to a sample with repeated elements.
-        # We run this test on random.Random() which makes deterministic selections
-        # for a given seed value.
-        sample = random.sample
-        seed = random.seed
-
-        colors =  ['red', 'green', 'blue', 'orange', 'black', 'amber']
-        counts = [500,      200,     20,       10,       5,       1 ]
-        k = 700
-        seed(8675309)
-        s1 = sample(colors, counts=counts, k=k)
-        seed(8675309)
-        expanded = [color for (color, count) in zip(colors, counts) for i in range(count)]
-        self.assertEqual(len(expanded), sum(counts))
-        s2 = sample(expanded, k=k)
-        self.assertEqual(s1, s2)
-
-        pop = 'abcdefghi'
-        counts = [10, 9, 8, 7, 6, 5, 4, 3, 2]
-        seed(8675309)
-        s1 = ''.join(sample(pop, counts=counts, k=30))
-        expanded = ''.join([letter for (letter, count) in zip(pop, counts) for i in range(count)])
-        seed(8675309)
-        s2 = ''.join(sample(expanded, k=30))
-        self.assertEqual(s1, s2)
-
     def test_choices(self):
         choices = self.gen.choices
         data = ['red', 'green', 'blue', 'yellow']
@@ -888,6 +861,33 @@ def test_randbytes_getrandbits(self):
             self.assertEqual(self.gen.randbytes(n),
                              gen2.getrandbits(n * 8).to_bytes(n, 'little'))
 
+    def test_sample_counts_equivalence(self):
+        # Test the documented strong equivalence to a sample with repeated elements.
+        # We run this test on random.Random() which makes deterministic selections
+        # for a given seed value.
+        sample = self.gen.sample
+        seed = self.gen.seed
+
+        colors =  ['red', 'green', 'blue', 'orange', 'black', 'amber']
+        counts = [500,      200,     20,       10,       5,       1 ]
+        k = 700
+        seed(8675309)
+        s1 = sample(colors, counts=counts, k=k)
+        seed(8675309)
+        expanded = [color for (color, count) in zip(colors, counts) for i in range(count)]
+        self.assertEqual(len(expanded), sum(counts))
+        s2 = sample(expanded, k=k)
+        self.assertEqual(s1, s2)
+
+        pop = 'abcdefghi'
+        counts = [10, 9, 8, 7, 6, 5, 4, 3, 2]
+        seed(8675309)
+        s1 = ''.join(sample(pop, counts=counts, k=30))
+        expanded = ''.join([letter for (letter, count) in zip(pop, counts) for i in range(count)])
+        seed(8675309)
+        s2 = ''.join(sample(expanded, k=30))
+        self.assertEqual(s1, s2)
+
 
 def gamma(z, sqrt2pi=(2.0*pi)**0.5):
     # Reflection to right half of complex plane

Misc/NEWS.d/next/Library/2021-01-18-10-41-44.bpo-42944.RrONvy.rst

@@ -0,0 +1 @@
+Fix ``random.Random.sample`` when ``counts`` argument is not ``None``.