fixes

Author: topper-123

doc/source/whatsnew/v1.2.0.rst

@@ -523,7 +523,7 @@ Categorical
 - :meth:`Categorical.fillna` will always return a copy, validate a passed fill value regardless of whether there are any NAs to fill, and disallow an ``NaT`` as a fill value for numeric categories (:issue:`36530`)
 - Bug in :meth:`Categorical.__setitem__` that incorrectly raised when trying to set a tuple value (:issue:`20439`)
 - Bug in :meth:`CategoricalIndex.equals` incorrectly casting non-category entries to ``np.nan`` (:issue:`37667`)
-- Bug in :meth:`Categorical.unique` where dtype was changed, it there were unused categories (:issue:`xxxxx`).
+- Bug in :meth:`Categorical.unique` where the dtype changes in the unique array if there are unused categories in the original array (:issue:`38140`).
 - Bug in :meth:`CategoricalIndex.where` incorrectly setting non-category entries to ``np.nan`` instead of raising ``TypeError`` (:issue:`37977`)
 -
 

pandas/tests/arrays/categorical/test_analytics.py

@@ -189,7 +189,7 @@ def test_searchsorted(self, ordered):
             ser.searchsorted(["bread", "cucumber"])
 
     def test_unique(self, ordered):
-        # GHXXXXX
+        # GH38140
         dtype = CategoricalDtype(["a", "b", "c"], ordered=ordered)
 
         # categories are reordered based on value when ordered=False
@@ -213,7 +213,7 @@ def test_unique(self, ordered):
         tm.assert_categorical_equal(res, exp_cat)
 
     def test_unique_index_series(self, ordered):
-        # GHXXXXX
+        # GH38140
         dtype = CategoricalDtype([3, 2, 1], ordered=ordered)
 
         c = Categorical([3, 1, 2, 2, 1], dtype=dtype)