Backport PR pandas-dev#54586: REF: Refactor conversion of na value

pandas/tests/strings/__init__.py

@@ -1,2 +1,12 @@
 # Needed for new arrow string dtype
+
+import pandas as pd
+
 object_pyarrow_numpy = ("object",)
+
+
+def _convert_na_value(ser, expected):
+    if ser.dtype != object:
+        # GH#18463
+        expected = expected.fillna(pd.NA)
+    return expected

pandas/tests/strings/test_find_replace.py

@@ -11,7 +11,10 @@
     Series,
     _testing as tm,
 )
-from pandas.tests.strings import object_pyarrow_numpy
+from pandas.tests.strings import (
+    _convert_na_value,
+    object_pyarrow_numpy,
+)
 
 # --------------------------------------------------------------------------------------
 # str.contains
@@ -758,9 +761,7 @@ def test_findall(any_string_dtype):
     ser = Series(["fooBAD__barBAD", np.nan, "foo", "BAD"], dtype=any_string_dtype)
     result = ser.str.findall("BAD[_]*")
     expected = Series([["BAD__", "BAD"], np.nan, [], ["BAD"]])
-    if ser.dtype != object:
-        # GH#18463
-        expected = expected.fillna(pd.NA)
+    expected = _convert_na_value(ser, expected)
     tm.assert_series_equal(result, expected)
 
 

pandas/tests/strings/test_split_partition.py

@@ -12,6 +12,7 @@
     Series,
     _testing as tm,
 )
+from pandas.tests.strings import _convert_na_value
 
 
 @pytest.mark.parametrize("method", ["split", "rsplit"])
@@ -20,9 +21,7 @@ def test_split(any_string_dtype, method):
 
     result = getattr(values.str, method)("_")
     exp = Series([["a", "b", "c"], ["c", "d", "e"], np.nan, ["f", "g", "h"]])
-    if values.dtype != object:
-        # GH#18463
-        exp = exp.fillna(pd.NA)
+    exp = _convert_na_value(values, exp)
     tm.assert_series_equal(result, exp)
 
 
@@ -32,9 +31,7 @@ def test_split_more_than_one_char(any_string_dtype, method):
     values = Series(["a__b__c", "c__d__e", np.nan, "f__g__h"], dtype=any_string_dtype)
     result = getattr(values.str, method)("__")
     exp = Series([["a", "b", "c"], ["c", "d", "e"], np.nan, ["f", "g", "h"]])
-    if values.dtype != object:
-        # GH#18463
-        exp = exp.fillna(pd.NA)
+    exp = _convert_na_value(values, exp)
     tm.assert_series_equal(result, exp)
 
     result = getattr(values.str, method)("__", expand=False)
@@ -46,9 +43,7 @@ def test_split_more_regex_split(any_string_dtype):
     values = Series(["a,b_c", "c_d,e", np.nan, "f,g,h"], dtype=any_string_dtype)
     result = values.str.split("[,_]")
     exp = Series([["a", "b", "c"], ["c", "d", "e"], np.nan, ["f", "g", "h"]])
-    if values.dtype != object:
-        # GH#18463
-        exp = exp.fillna(pd.NA)
+    exp = _convert_na_value(values, exp)
     tm.assert_series_equal(result, exp)
 
 
@@ -128,9 +123,7 @@ def test_rsplit(any_string_dtype):
     values = Series(["a,b_c", "c_d,e", np.nan, "f,g,h"], dtype=any_string_dtype)
     result = values.str.rsplit("[,_]")
     exp = Series([["a,b_c"], ["c_d,e"], np.nan, ["f,g,h"]])
-    if values.dtype != object:
-        # GH#18463
-        exp = exp.fillna(pd.NA)
+    exp = _convert_na_value(values, exp)
     tm.assert_series_equal(result, exp)
 
 
@@ -139,9 +132,7 @@ def test_rsplit_max_number(any_string_dtype):
     values = Series(["a_b_c", "c_d_e", np.nan, "f_g_h"], dtype=any_string_dtype)
     result = values.str.rsplit("_", n=1)
     exp = Series([["a_b", "c"], ["c_d", "e"], np.nan, ["f_g", "h"]])
-    if values.dtype != object:
-        # GH#18463
-        exp = exp.fillna(pd.NA)
+    exp = _convert_na_value(values, exp)
     tm.assert_series_equal(result, exp)
 
 
@@ -455,9 +446,7 @@ def test_partition_series_more_than_one_char(method, exp, any_string_dtype):
     s = Series(["a__b__c", "c__d__e", np.nan, "f__g__h", None], dtype=any_string_dtype)
     result = getattr(s.str, method)("__", expand=False)
     expected = Series(exp)
-    if s.dtype != object:
-        # GH#18463
-        expected = expected.fillna(pd.NA)
+    expected = _convert_na_value(s, expected)
     tm.assert_series_equal(result, expected)
 
 
@@ -480,9 +469,7 @@ def test_partition_series_none(any_string_dtype, method, exp):
     s = Series(["a b c", "c d e", np.nan, "f g h", None], dtype=any_string_dtype)
     result = getattr(s.str, method)(expand=False)
     expected = Series(exp)
-    if s.dtype != object:
-        # GH#18463
-        expected = expected.fillna(pd.NA)
+    expected = _convert_na_value(s, expected)
     tm.assert_series_equal(result, expected)
 
 
@@ -505,9 +492,7 @@ def test_partition_series_not_split(any_string_dtype, method, exp):
     s = Series(["abc", "cde", np.nan, "fgh", None], dtype=any_string_dtype)
     result = getattr(s.str, method)("_", expand=False)
     expected = Series(exp)
-    if s.dtype != object:
-        # GH#18463
-        expected = expected.fillna(pd.NA)
+    expected = _convert_na_value(s, expected)
     tm.assert_series_equal(result, expected)
 
 
@@ -531,9 +516,7 @@ def test_partition_series_unicode(any_string_dtype, method, exp):
 
     result = getattr(s.str, method)("_", expand=False)
     expected = Series(exp)
-    if s.dtype != object:
-        # GH#18463
-        expected = expected.fillna(pd.NA)
+    expected = _convert_na_value(s, expected)
     tm.assert_series_equal(result, expected)