BUG: Series(nullable).tolist() -> numpy scalars (#49890)

Author: lukemanley

doc/source/whatsnew/v2.0.0.rst

@@ -766,6 +766,7 @@ Sparse
 ExtensionArray
 ^^^^^^^^^^^^^^
 - Bug in :meth:`Series.mean` overflowing unnecessarily with nullable integers (:issue:`48378`)
+- Bug in :meth:`Series.tolist` for nullable dtypes returning numpy scalars instead of python scalars (:issue:`49890`)
 - Bug when concatenating an empty DataFrame with an ExtensionDtype to another DataFrame with the same ExtensionDtype, the resulting dtype turned into object (:issue:`48510`)
 -
 

pandas/core/arrays/masked.py

@@ -436,10 +436,8 @@ def to_numpy(
     def tolist(self):
         if self.ndim > 1:
             return [x.tolist() for x in self]
-        if not self._hasna:
-            # faster than list(self)
-            return list(self._data)
-        return list(self)
+        dtype = None if self._hasna else self._data.dtype
+        return self.to_numpy(dtype=dtype).tolist()
 
     @overload
     def astype(self, dtype: npt.DTypeLike, copy: bool = ...) -> np.ndarray:

pandas/tests/series/methods/test_tolist.py

@@ -0,0 +1,36 @@
+import pytest
+
+import pandas.util._test_decorators as td
+
+from pandas import (
+    Interval,
+    Period,
+    Series,
+    Timedelta,
+    Timestamp,
+)
+
+
+@pytest.mark.parametrize(
+    "values, dtype, expected_dtype",
+    (
+        ([1], "int64", int),
+        ([1], "Int64", int),
+        ([1.0], "float64", float),
+        ([1.0], "Float64", float),
+        (["abc"], "object", str),
+        (["abc"], "string", str),
+        ([Interval(1, 3)], "interval", Interval),
+        ([Period("2000-01-01", "D")], "period[D]", Period),
+        ([Timedelta(days=1)], "timedelta64[ns]", Timedelta),
+        ([Timestamp("2000-01-01")], "datetime64[ns]", Timestamp),
+        pytest.param([1], "int64[pyarrow]", int, marks=td.skip_if_no("pyarrow")),
+        pytest.param([1.0], "float64[pyarrow]", float, marks=td.skip_if_no("pyarrow")),
+        pytest.param(["abc"], "string[pyarrow]", str, marks=td.skip_if_no("pyarrow")),
+    ),
+)
+def test_tolist_scalar_dtype(values, dtype, expected_dtype):
+    # GH49890
+    ser = Series(values, dtype=dtype)
+    result_dtype = type(ser.tolist()[0])
+    assert result_dtype == expected_dtype