bpo-44150: Support optional weights parameter for fmean() (GH-26175)

1 files changed, 21 insertions, 0 deletions

diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py
index 70d269d..3e6e17a 100644
--- a/Lib/test/test_statistics.py
+++ b/Lib/test/test_statistics.py
@@ -1972,6 +1972,27 @@ class TestFMean(unittest.TestCase):
         with self.assertRaises(ValueError):
             fmean([Inf, -Inf])
 
+    def test_weights(self):
+        fmean = statistics.fmean
+        StatisticsError = statistics.StatisticsError
+        self.assertEqual(
+            fmean([10, 10, 10, 50], [0.25] * 4),
+            fmean([10, 10, 10, 50]))
+        self.assertEqual(
+            fmean([10, 10, 20], [0.25, 0.25, 0.50]),
+            fmean([10, 10, 20, 20]))
+        self.assertEqual(                           # inputs are iterators
+            fmean(iter([10, 10, 20]), iter([0.25, 0.25, 0.50])),
+            fmean([10, 10, 20, 20]))
+        with self.assertRaises(StatisticsError):
+            fmean([10, 20, 30], [1, 2])             # unequal lengths
+        with self.assertRaises(StatisticsError):
+            fmean(iter([10, 20, 30]), iter([1, 2])) # unequal lengths
+        with self.assertRaises(StatisticsError):
+            fmean([10, 20], [-1, 1])                # sum of weights is zero
+        with self.assertRaises(StatisticsError):
+            fmean(iter([10, 20]), iter([-1, 1]))    # sum of weights is zero
+
 
 # === Tests for variances and standard deviations ===