Add as_unit method to Timestamp

Author: skatsuta

pandas-stubs/_libs/tslibs/timestamps.pyi

@@ -312,3 +312,6 @@ class Timestamp(datetime):
     def daysinmonth(self) -> int: ...
     @property
     def unit(self) -> str: ...
+    def as_unit(
+        self, unit: Literal["s", "ms", "us", "ns"], round_ok: bool = ...
+    ) -> Self: ...

tests/test_scalars.py

@@ -1646,6 +1646,11 @@ def test_timestamp_misc_methods() -> None:
             pd.Timestamp,
         )
 
+    check(assert_type(ts2.as_unit("s"), pd.Timestamp), pd.Timestamp)
+    check(assert_type(ts2.as_unit("ms"), pd.Timestamp), pd.Timestamp)
+    check(assert_type(ts2.as_unit("us", round_ok=True), pd.Timestamp), pd.Timestamp)
+    check(assert_type(ts2.as_unit("ns", round_ok=False), pd.Timestamp), pd.Timestamp)
+
 
 def test_timestamp_types_arithmetic() -> None:
     ts: pd.Timestamp = pd.to_datetime("2021-03-01")