done

lib/python3.11/site-packages/pandas/tests/arrays/datetimes/test_cumulative.py

@@ -0,0 +1,44 @@
+import pytest
+
+import pandas._testing as tm
+from pandas.core.arrays import DatetimeArray
+
+
+class TestAccumulator:
+    def test_accumulators_freq(self):
+        # GH#50297
+        arr = DatetimeArray._from_sequence(
+            [
+                "2000-01-01",
+                "2000-01-02",
+                "2000-01-03",
+            ],
+            dtype="M8[ns]",
+        )._with_freq("infer")
+        result = arr._accumulate("cummin")
+        expected = DatetimeArray._from_sequence(["2000-01-01"] * 3, dtype="M8[ns]")
+        tm.assert_datetime_array_equal(result, expected)
+
+        result = arr._accumulate("cummax")
+        expected = DatetimeArray._from_sequence(
+            [
+                "2000-01-01",
+                "2000-01-02",
+                "2000-01-03",
+            ],
+            dtype="M8[ns]",
+        )
+        tm.assert_datetime_array_equal(result, expected)
+
+    @pytest.mark.parametrize("func", ["cumsum", "cumprod"])
+    def test_accumulators_disallowed(self, func):
+        # GH#50297
+        arr = DatetimeArray._from_sequence(
+            [
+                "2000-01-01",
+                "2000-01-02",
+            ],
+            dtype="M8[ns]",
+        )._with_freq("infer")
+        with pytest.raises(TypeError, match=f"Accumulation {func}"):
+            arr._accumulate(func)