Issue #20478: avoid special casing Counter in statistics

Passing Counter objects to the Counter constructor is
special cased, going through iter() firsts ensures they
are handled the same way as any other iterable.

(Committing on Steven's behalf as I don't believe his
SSH key is registered yet)

1 files changed, 8 insertions, 0 deletions

diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py
index 3d30d88f69..6db821fc6e 100644
--- a/Lib/test/test_statistics.py
+++ b/Lib/test/test_statistics.py
@@ -1355,6 +1355,14 @@ class TestMode(NumericTestCase, AverageMixin, UnivariateTypeMixin):
         # collections.Counter, which accepts None and returns an empty dict.
         self.assertRaises(TypeError, self.func, None)
 
+    def test_counter_data(self):
+        # Test that a Counter is treated like any other iterable.
+        data = collections.Counter([1, 1, 1, 2])
+        # Since the keys of the counter are treated as data points, not the
+        # counts, this should raise.
+        self.assertRaises(statistics.StatisticsError, self.func, data)
+
+
 
 # === Tests for variances and standard deviations ===