testcase for pandas-dev#33168 Quantile function fails when performing groupby on Time Zone Aware Timestamps

Author: dannyi96

pandas/tests/groupby/test_quantile.py

@@ -343,3 +343,50 @@ def test_columns_groupby_quantile():
     )
 
     tm.assert_frame_equal(result, expected)
+
+def test_timestamp_groupby_quantile():
+    # GH 33168
+    df = DataFrame(
+        {
+            'timestamp': pd.date_range(start='2020-04-19 00:00:00', freq='1T', periods=200, tz='UTC').floor('1H'),
+            'category': list(range(1, 201)),
+            'value': list(range(201, 401))
+        }
+    )
+            
+    result = df.groupby('timestamp').quantile([0.1, 0.5, 0.9])
+    
+    expected = DataFrame(
+        [
+                {'category': 6.9, 'value': 206.9}, 
+                {'category': 30.5, 'value': 230.5}, 
+                {'category': 54.1, 'value': 254.1}, 
+                {'category': 66.9, 'value': 266.9}, 
+                {'category': 90.5, 'value': 290.5}, 
+                {'category': 114.1, 'value': 314.1}, 
+                {'category': 126.9, 'value': 326.9}, 
+                {'category': 150.5, 'value': 350.5}, 
+                {'category': 174.1, 'value': 374.1}, 
+                {'category': 182.9, 'value': 382.9}, 
+                {'category': 190.5, 'value': 390.5}, 
+                {'category': 198.1, 'value': 398.1}
+        ], 
+        index=pd.MultiIndex.from_tuples(
+            [
+                ( pd.Timestamp('2020-04-19 00:00:00+00:00'), 0.1),
+                ( pd.Timestamp('2020-04-19 00:00:00+00:00'), 0.5),
+                ( pd.Timestamp('2020-04-19 00:00:00+00:00'), 0.9),
+                ( pd.Timestamp('2020-04-19 01:00:00+00:00'), 0.1),
+                ( pd.Timestamp('2020-04-19 01:00:00+00:00'), 0.5),
+                ( pd.Timestamp('2020-04-19 01:00:00+00:00'), 0.9),
+                ( pd.Timestamp('2020-04-19 02:00:00+00:00'), 0.1),
+                ( pd.Timestamp('2020-04-19 02:00:00+00:00'), 0.5),
+                ( pd.Timestamp('2020-04-19 02:00:00+00:00'), 0.9),
+                ( pd.Timestamp('2020-04-19 03:00:00+00:00'), 0.1),
+                ( pd.Timestamp('2020-04-19 03:00:00+00:00'), 0.5),
+                ( pd.Timestamp('2020-04-19 03:00:00+00:00'), 0.9)
+            ], names=('timestamp', None)
+        )
+    )
+        
+    tm.assert_frame_equal(result, expected)