Bug: Resample ignoring closed=right for TimedeltaIndex

doc/source/whatsnew/v1.5.0.rst

@@ -241,7 +241,7 @@ Plotting
 
 Groupby/resample/rolling
 ^^^^^^^^^^^^^^^^^^^^^^^^
--
+- Bug in :meth:`DataFrame.resample` ignoring ``closed="right"`` on :class:`TimedeltaIndex` (:issue:`45414`)
 -
 
 Reshaping

pandas/core/resample.py

@@ -1702,12 +1702,19 @@ def _get_time_delta_bins(self, ax: TimedeltaIndex):
             return binner, [], labels
 
         start, end = ax.min(), ax.max()
+
+        if self.closed == "right":
+            end += self.freq
+
         labels = binner = timedelta_range(
             start=start, end=end, freq=self.freq, name=ax.name
         )
 
-        end_stamps = labels + self.freq
-        bins = ax.searchsorted(end_stamps, side="left")
+        end_stamps = labels
+        if self.closed == "left":
+            end_stamps += self.freq
+
+        bins = ax.searchsorted(end_stamps, side=self.closed)
 
         if self.offset:
             # GH 10530 & 31809

pandas/tests/resample/test_timedelta.py

@@ -191,3 +191,17 @@ def test_resample_quantile_timedelta():
         index=pd.date_range("20200101", periods=2, tz="UTC", freq="2D"),
     )
     tm.assert_frame_equal(result, expected)
+
+
+def test_resample_closed_right():
+    # GH#45414
+    idx = pd.Index([pd.Timedelta(seconds=120 + i * 30) for i in range(10)])
+    ser = Series(range(10), index=idx)
+    result = ser.resample("T", closed="right", label="right").sum()
+    expected = Series(
+        [0, 3, 7, 11, 15, 9],
+        index=pd.TimedeltaIndex(
+            [pd.Timedelta(seconds=120 + i * 60) for i in range(6)], freq="T"
+        ),
+    )
+    tm.assert_series_equal(result, expected)