REF: DatetimeIndex test_insert, test_delete

pandas/tests/indexes/datetimes/test_delete.py

@@ -0,0 +1,134 @@
+import pytest
+
+from pandas import DatetimeIndex, Series, date_range
+import pandas._testing as tm
+
+
+class TestDelete:
+    def test_delete(self):
+        idx = date_range(start="2000-01-01", periods=5, freq="M", name="idx")
+
+        # preserve freq
+        expected_0 = date_range(start="2000-02-01", periods=4, freq="M", name="idx")
+        expected_4 = date_range(start="2000-01-01", periods=4, freq="M", name="idx")
+
+        # reset freq to None
+        expected_1 = DatetimeIndex(
+            ["2000-01-31", "2000-03-31", "2000-04-30", "2000-05-31"],
+            freq=None,
+            name="idx",
+        )
+
+        cases = {
+            0: expected_0,
+            -5: expected_0,
+            -1: expected_4,
+            4: expected_4,
+            1: expected_1,
+        }
+        for n, expected in cases.items():
+            result = idx.delete(n)
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freq == expected.freq
+
+        with pytest.raises((IndexError, ValueError), match="out of bounds"):
+            # either depending on numpy version
+            idx.delete(5)
+
+        for tz in [None, "Asia/Tokyo", "US/Pacific"]:
+            idx = date_range(
+                start="2000-01-01 09:00", periods=10, freq="H", name="idx", tz=tz
+            )
+
+            expected = date_range(
+                start="2000-01-01 10:00", periods=9, freq="H", name="idx", tz=tz
+            )
+            result = idx.delete(0)
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freqstr == "H"
+            assert result.tz == expected.tz
+
+            expected = date_range(
+                start="2000-01-01 09:00", periods=9, freq="H", name="idx", tz=tz
+            )
+            result = idx.delete(-1)
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freqstr == "H"
+            assert result.tz == expected.tz
+
+    def test_delete_slice(self):
+        idx = date_range(start="2000-01-01", periods=10, freq="D", name="idx")
+
+        # preserve freq
+        expected_0_2 = date_range(start="2000-01-04", periods=7, freq="D", name="idx")
+        expected_7_9 = date_range(start="2000-01-01", periods=7, freq="D", name="idx")
+
+        # reset freq to None
+        expected_3_5 = DatetimeIndex(
+            [
+                "2000-01-01",
+                "2000-01-02",
+                "2000-01-03",
+                "2000-01-07",
+                "2000-01-08",
+                "2000-01-09",
+                "2000-01-10",
+            ],
+            freq=None,
+            name="idx",
+        )
+
+        cases = {
+            (0, 1, 2): expected_0_2,
+            (7, 8, 9): expected_7_9,
+            (3, 4, 5): expected_3_5,
+        }
+        for n, expected in cases.items():
+            result = idx.delete(n)
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freq == expected.freq
+
+            result = idx.delete(slice(n[0], n[-1] + 1))
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freq == expected.freq
+
+        for tz in [None, "Asia/Tokyo", "US/Pacific"]:
+            ts = Series(
+                1,
+                index=date_range(
+                    "2000-01-01 09:00", periods=10, freq="H", name="idx", tz=tz
+                ),
+            )
+            # preserve freq
+            result = ts.drop(ts.index[:5]).index
+            expected = date_range(
+                "2000-01-01 14:00", periods=5, freq="H", name="idx", tz=tz
+            )
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freq == expected.freq
+            assert result.tz == expected.tz
+
+            # reset freq to None
+            result = ts.drop(ts.index[[1, 3, 5, 7, 9]]).index
+            expected = DatetimeIndex(
+                [
+                    "2000-01-01 09:00",
+                    "2000-01-01 11:00",
+                    "2000-01-01 13:00",
+                    "2000-01-01 15:00",
+                    "2000-01-01 17:00",
+                ],
+                freq=None,
+                name="idx",
+                tz=tz,
+            )
+            tm.assert_index_equal(result, expected)
+            assert result.name == expected.name
+            assert result.freq == expected.freq
+            assert result.tz == expected.tz