various

Author: topper-123

pandas/core/arrays/base.py

@@ -41,7 +41,7 @@
 )
 from pandas.core.dtypes.dtypes import ExtensionDtype
 from pandas.core.dtypes.generic import ABCDataFrame, ABCIndexClass, ABCSeries
-from pandas.core.dtypes.missing import isna
+from pandas.core.dtypes.missing import is_valid_nat_for_dtype, isna
 
 from pandas.core import ops
 from pandas.core.algorithms import factorize_array, unique
@@ -360,7 +360,7 @@ def __contains__(self, item) -> bool:
         """
         # comparisons of any item to pd.NA always return pd.NA, so e.g. "a" in [pd.NA]
         # would raise a TypeError. The implementation below works around that.
-        if isna(item):
+        if is_valid_nat_for_dtype(item, self.dtype):
             return isna(self).any() if self._can_hold_na else False
         else:
             return (item == self).any()

pandas/tests/arrays/categorical/test_operators.py

@@ -401,14 +401,17 @@ def test_contains(self, ordered):
         cat = Categorical(["a", "b"], ordered=ordered)
         assert "a" in cat
         assert "x" not in cat
+        assert np.nan not in cat
         assert pd.NA not in cat
 
         cat = Categorical([np.nan, "a"], ordered=ordered)
         assert "a" in cat
         assert "x" not in cat
+        assert np.nan in cat
         assert pd.NA in cat
 
         cat = cat[::-1]
         assert "a" in cat
         assert "x" not in cat
+        assert np.nan in cat
         assert pd.NA in cat

pandas/tests/arrays/string_/test_string.py

@@ -524,3 +524,19 @@ def test_to_numpy_na_value(dtype, nulls_fixture):
     result = arr.to_numpy(na_value=na_value)
     expected = np.array(["a", na_value, "b"], dtype=object)
     tm.assert_numpy_array_equal(result, expected)
+
+
+def test_contains():
+    # GH-xxxxx
+    arr = pd.array(np.array(["a", "b"], dtype="string"))
+
+    assert "a" in arr
+    assert "x" not in arr
+    assert np.nan not in arr
+    assert pd.NA not in arr
+
+    arr = pd.arrays.StringArray(np.array(["a", pd.NA]))
+    assert "a" in arr
+    assert "x" not in arr
+    assert np.nan in arr
+    assert pd.NA in arr