Issue27139 patch by Julio C Cardoza.

Steven D'Aprano · Steven D'Aprano · commit 8c115a46e7c6 · 2016-07-08T02:38:45.000+10:00
diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py
@@ -1600,6 +1600,22 @@ def test_interval(self):
         data = [220, 220, 240, 260, 260, 260, 260, 280, 280, 300, 320, 340]
         self.assertEqual(self.func(data, 20), 265.0)
 
+    def test_data_type_error(self):
+        # Test median_grouped with str, bytes data types for data and interval
+        data = ["", "", ""]
+        self.assertRaises(TypeError, self.func, data)
+        #---
+        data = [b"", b"", b""]
+        self.assertRaises(TypeError, self.func, data)
+        #---
+        data = [1, 2, 3]
+        interval = ""
+        self.assertRaises(TypeError, self.func, data, interval)
+        #---
+        data = [1, 2, 3]
+        interval = b""
+        self.assertRaises(TypeError, self.func, data, interval)
+
 
 class TestMode(NumericTestCase, AverageMixin, UnivariateTypeMixin):
     # Test cases for the discrete version of mode.
