From 77188e0e04db70c7a1bb63008388791db37ed810 Mon Sep 17 00:00:00 2001
From: Richard Shadrach <45562402+rhshadrach@users.noreply.github.com>
Date: Fri, 2 Feb 2024 17:54:29 -0500
Subject: [PATCH] DEPR: Enforce deprecation of groupby(...).grouper (#57207)

---
 doc/source/whatsnew/v3.0.0.rst        |  1 +
 pandas/core/groupby/groupby.py        | 11 -----------
 pandas/core/groupby/grouper.py        | 11 -----------
 pandas/tests/groupby/test_grouping.py | 17 +++--------------
 4 files changed, 4 insertions(+), 36 deletions(-)

diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
index 73776c2d6ee21..25163a0f678b0 100644
--- a/doc/source/whatsnew/v3.0.0.rst
+++ b/doc/source/whatsnew/v3.0.0.rst
@@ -103,6 +103,7 @@ Deprecations
 Removal of prior version deprecations/changes
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 - Removed :meth:`DataFrameGroupby.fillna` and :meth:`SeriesGroupBy.fillna` (:issue:`55719`)
+- Removed ``DataFrameGroupBy.grouper`` and ``SeriesGroupBy.grouper`` (:issue:`56521`)
 - Removed ``axis`` argument from :meth:`DataFrame.groupby`, :meth:`Series.groupby`, :meth:`DataFrame.rolling`, :meth:`Series.rolling`, :meth:`DataFrame.resample`, and :meth:`Series.resample` (:issue:`51203`)
 - Removed ``axis`` argument from all groupby operations (:issue:`50405`)
 - Removed deprecated argument ``obj`` in :meth:`.DataFrameGroupBy.get_group` and :meth:`.SeriesGroupBy.get_group` (:issue:`53545`)
diff --git a/pandas/core/groupby/groupby.py b/pandas/core/groupby/groupby.py
index 68626534f1e74..64f882e5a146c 100644
--- a/pandas/core/groupby/groupby.py
+++ b/pandas/core/groupby/groupby.py
@@ -794,17 +794,6 @@ def __repr__(self) -> str:
         # TODO: Better repr for GroupBy object
         return object.__repr__(self)
 
-    @final
-    @property
-    def grouper(self) -> ops.BaseGrouper:
-        warnings.warn(
-            f"{type(self).__name__}.grouper is deprecated and will be removed in a "
-            "future version of pandas.",
-            category=FutureWarning,
-            stacklevel=find_stack_level(),
-        )
-        return self._grouper
-
     @final
     @property
     def groups(self) -> dict[Hashable, np.ndarray]:
diff --git a/pandas/core/groupby/grouper.py b/pandas/core/groupby/grouper.py
index 4b9cf5ab75525..f377c9d03d05a 100644
--- a/pandas/core/groupby/grouper.py
+++ b/pandas/core/groupby/grouper.py
@@ -428,17 +428,6 @@ def obj(self):
         )
         return self._obj_deprecated
 
-    @final
-    @property
-    def grouper(self):
-        warnings.warn(
-            f"{type(self).__name__}.grouper is deprecated and will be removed "
-            "in a future version. Use GroupBy.grouper instead.",
-            FutureWarning,
-            stacklevel=find_stack_level(),
-        )
-        return self._grouper_deprecated
-
     @final
     @property
     def groups(self):
diff --git a/pandas/tests/groupby/test_grouping.py b/pandas/tests/groupby/test_grouping.py
index 841dd29edab10..ee1df1242442f 100644
--- a/pandas/tests/groupby/test_grouping.py
+++ b/pandas/tests/groupby/test_grouping.py
@@ -414,9 +414,7 @@ def test_grouper_getting_correct_binner(self):
 
     def test_grouper_iter(self, df):
         gb = df.groupby("A")
-        msg = "DataFrameGroupBy.grouper is deprecated"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            grouper = gb.grouper
+        grouper = gb._grouper
         result = sorted(grouper)
         expected = ["bar", "foo"]
         assert result == expected
@@ -428,9 +426,7 @@ def test_empty_groups(self, df):
 
     def test_groupby_grouper(self, df):
         grouped = df.groupby("A")
-        msg = "DataFrameGroupBy.grouper is deprecated"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            grouper = grouped.grouper
+        grouper = grouped._grouper
         result = df.groupby(grouper).mean(numeric_only=True)
         expected = grouped.mean(numeric_only=True)
         tm.assert_frame_equal(result, expected)
@@ -791,9 +787,7 @@ def test_groupby_empty(self):
 
         # check name
         gb = s.groupby(s)
-        msg = "SeriesGroupBy.grouper is deprecated"
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            grouper = gb.grouper
+        grouper = gb._grouper
         result = grouper.names
         expected = ["name"]
         assert result == expected
@@ -1155,11 +1149,6 @@ def test_grouper_groups():
         res = grper.groups
     assert res is gb.groups
 
-    msg = "Use GroupBy.grouper instead"
-    with tm.assert_produces_warning(FutureWarning, match=msg):
-        res = grper.grouper
-    assert res is gb._grouper
-
     msg = "Grouper.obj is deprecated and will be removed"
     with tm.assert_produces_warning(FutureWarning, match=msg):
         res = grper.obj