From d6ec2ba227fd454f4c5dd5149d897a05bdb0d6b7 Mon Sep 17 00:00:00 2001
From: zmoon <zmoon92@gmail.com>
Date: Wed, 1 Mar 2023 17:41:11 -0700
Subject: [PATCH 1/4] Add test for Series as CategoricalDtype

---
 tests/test_series.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/tests/test_series.py b/tests/test_series.py
index 169fddb5d..d5850eaf6 100644
--- a/tests/test_series.py
+++ b/tests/test_series.py
@@ -1591,3 +1591,15 @@ def test_updated_astype() -> None:
         pd.Series,
         Decimal,
     )
+
+    # Categorical
+    check(
+        assert_type(s.astype(pd.CategoricalDtype()), "pd.Series[Any]"),
+        pd.Series,
+        pd.CategoricalDtype,
+    )
+    check(
+        assert_type(s.astype("category"), "pd.Series[Any]"),
+        pd.Series,
+        pd.CategoricalDtype,
+    )

From db99baf403999b8365f5733a86f569b09b9a5fb7 Mon Sep 17 00:00:00 2001
From: zmoon <zmoon92@gmail.com>
Date: Wed, 1 Mar 2023 17:43:49 -0700
Subject: [PATCH 2/4] Add `CategoryDtypeArg` to `AstypeArg`

---
 pandas-stubs/_typing.pyi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pandas-stubs/_typing.pyi b/pandas-stubs/_typing.pyi
index 935d43470..7cf6eb9d1 100644
--- a/pandas-stubs/_typing.pyi
+++ b/pandas-stubs/_typing.pyi
@@ -160,6 +160,7 @@ AstypeArg: TypeAlias = (
     | TimedeltaDtypeArg
     | TimestampDtypeArg
     | CategoricalDtype
+    | CategoryDtypeArg
     | ExtensionDtype
 )
 # DtypeArg specifies all allowable dtypes in a functions its dtype argument

From 48177b53e4961ab2e10a10f7fd37420e6af8ae46 Mon Sep 17 00:00:00 2001
From: zmoon <zmoon92@gmail.com>
Date: Wed, 1 Mar 2023 20:20:47 -0700
Subject: [PATCH 3/4] Apply review suggestions

---
 pandas-stubs/_typing.pyi | 3 +--
 tests/test_series.py     | 4 ++--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/pandas-stubs/_typing.pyi b/pandas-stubs/_typing.pyi
index 7cf6eb9d1..8c8fee8b4 100644
--- a/pandas-stubs/_typing.pyi
+++ b/pandas-stubs/_typing.pyi
@@ -148,7 +148,7 @@ ComplexDtypeArg: TypeAlias = (
 )
 TimedeltaDtypeArg: TypeAlias = Literal["timedelta64[ns]"]
 TimestampDtypeArg: TypeAlias = Literal["datetime64[ns]"]
-CategoryDtypeArg: TypeAlias = Literal["category"]
+CategoryDtypeArg: TypeAlias = CategoricalDtype | Literal["category"]
 
 AstypeArg: TypeAlias = (
     BooleanDtypeArg
@@ -159,7 +159,6 @@ AstypeArg: TypeAlias = (
     | ComplexDtypeArg
     | TimedeltaDtypeArg
     | TimestampDtypeArg
-    | CategoricalDtype
     | CategoryDtypeArg
     | ExtensionDtype
 )
diff --git a/tests/test_series.py b/tests/test_series.py
index d5850eaf6..63c2cd011 100644
--- a/tests/test_series.py
+++ b/tests/test_series.py
@@ -1596,10 +1596,10 @@ def test_updated_astype() -> None:
     check(
         assert_type(s.astype(pd.CategoricalDtype()), "pd.Series[Any]"),
         pd.Series,
-        pd.CategoricalDtype,
+        np.integer,
     )
     check(
         assert_type(s.astype("category"), "pd.Series[Any]"),
         pd.Series,
-        pd.CategoricalDtype,
+        np.integer,
     )

From 3770f4eaed8c4e8d0aea7c5dcf11177ea0f275a8 Mon Sep 17 00:00:00 2001
From: zmoon <zmoon92@gmail.com>
Date: Thu, 2 Mar 2023 15:44:28 -0700
Subject: [PATCH 4/4] Add test for `DataFrame.astype('category')`

---
 tests/test_frame.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tests/test_frame.py b/tests/test_frame.py
index 9be9b77e5..254cfc514 100644
--- a/tests/test_frame.py
+++ b/tests/test_frame.py
@@ -2442,3 +2442,5 @@ def test_astype() -> None:
         assert_type(ab.astype({"col1": "int32", "col2": str}), "pd.DataFrame"),
         pd.DataFrame,
     )
+    check(assert_type(s.astype(pd.CategoricalDtype()), "pd.DataFrame"), pd.DataFrame)
+    check(assert_type(s.astype("category"), "pd.DataFrame"), pd.DataFrame)  # GH 559