From 43a734edad120dd441bd374f2623c2b5dcd85e79 Mon Sep 17 00:00:00 2001
From: gfyoung <gfyoung17@gmail.com>
Date: Sun, 11 Jun 2017 14:51:55 -0700
Subject: [PATCH] TST: Add test for groupby sum of large ints

Closes gh-14758.
---
 pandas/tests/groupby/test_aggregate.py | 30 ++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/pandas/tests/groupby/test_aggregate.py b/pandas/tests/groupby/test_aggregate.py
index d7b46e6748b99b..0f8769014049d5 100644
--- a/pandas/tests/groupby/test_aggregate.py
+++ b/pandas/tests/groupby/test_aggregate.py
@@ -844,3 +844,33 @@ def test_agg_timezone_round_trip(self):
         ts = df['B'].iloc[2]
         assert ts == grouped.last()['B'].iloc[0]
         assert ts == grouped.apply(lambda x: x.iloc[-1])[0]
+
+    def test_sum_uint64_overflow(self):
+        # see gh-14758
+
+        # Convert to uint64
+        df = pd.DataFrame([[1, 2], [3, 4], [5, 6]],
+                          dtype=object) + 9223372036854775807
+
+        index = pd.Index([9223372036854775808, 9223372036854775810,
+                          9223372036854775812], dtype=np.uint64)
+        expected = pd.DataFrame({1: [9223372036854775809,
+                                     9223372036854775811,
+                                     9223372036854775813]}, index=index)
+
+        expected.index.name = 0
+        result = df.groupby(0).sum()
+        tm.assert_frame_equal(result, expected)
+
+        # Remain as object
+        df = pd.DataFrame([[1, 2], [3, 4], [5, 6]],
+                          dtype=object) + 19223372036854775807
+
+        index = pd.Index([19223372036854775808, 19223372036854775810,
+                          19223372036854775812], dtype=object)
+        expected = pd.DataFrame({1: [19223372036854775809,
+                                     19223372036854775811,
+                                     19223372036854775813]}, index=index)
+        expected.index.name = 0
+        result = df.groupby(0).sum()
+        tm.assert_frame_equal(result, expected)