Fixing code check and parameterizing unit tests.

doc/source/whatsnew/v2.2.0.rst

@@ -192,8 +192,8 @@ Other enhancements
 - :func:`tseries.api.guess_datetime_format` is now part of the public API (:issue:`54727`)
 - :meth:`ExtensionArray._explode` interface method added to allow extension type implementations of the ``explode`` method (:issue:`54833`)
 - :meth:`ExtensionArray.duplicated` added to allow extension type implementations of the ``duplicated`` method (:issue:`55255`)
-- Allow passing ``pat_dict`` argument to :meth:`pandas.Series.str.replace` (:issue:`51748`)
 - Allow passing ``read_only``, ``data_only`` and ``keep_links`` arguments to openpyxl using ``engine_kwargs`` of :func:`read_excel` (:issue:`55027`)
+- Allow passing ``repl_kwargs`` argument to :meth:`pandas.Series.str.replace` (:issue:`51748`)
 - DataFrame.apply now allows the usage of numba (via ``engine="numba"``) to JIT compile the passed function, allowing for potential speedups (:issue:`54666`)
 - Implement masked algorithms for :meth:`Series.value_counts` (:issue:`54984`)
 - Improved error message when constructing :class:`Period` with invalid offsets such as "QS" (:issue:`55785`)

pandas/core/strings/accessor.py

@@ -1400,7 +1400,7 @@ def replace(
         case: bool | None = None,
         flags: int = 0,
         regex: bool = False,
-        pat_dict: dict | None = None,
+        repl_kwargs: dict | None = None,
     ):
         r"""
         Replace each occurrence of pattern/regex in the Series/Index.
@@ -1435,8 +1435,8 @@ def replace(
             - If False, treats the pattern as a literal string
             - Cannot be set to False if `pat` is a compiled regex or `repl` is
               a callable.
-        pat_dict: dict, default None
-            <key: value> pairs representing strings to be replaced, and their
+        repl_kwargs : dict, default None
+            <key : value> pairs representing strings to be replaced, and their
             updated values.
 
         Returns
@@ -1460,10 +1460,10 @@ def replace(
 
         Examples
         --------
-        When `pat_dict` is a dictionary, every key in `pat_dict` is replaced
+        When `repl_kwargs` is a dictionary, every key in `repl_kwargs` is replaced
         with its corresponding value:
 
-        >>> pd.Series(['A', 'B', np.nan]).str.replace(pat_dict={'A': 'a', 'B': 'b'})
+        >>> pd.Series(['A', 'B', np.nan]).str.replace(repl_kwargs={'A': 'a', 'B': 'b'})
         0    a
         1    b
         2    NaN
@@ -1531,13 +1531,19 @@ def replace(
         2    NaN
         dtype: object
         """
-        if pat is None and pat_dict is None:
+        if pat is None and repl_kwargs is None:
             raise ValueError(
                 "Cannot replace a string without specifying a string to be modified."
             )
 
+        if pat is not None and repl_kwargs is not None:
+            raise ValueError(
+                "Cannot replace a string using both a pattern and <key : value> "
+                "combination."
+            )
+
         # Check whether repl is valid (GH 13438, GH 15055)
-        if not (isinstance(repl, str) or callable(repl)) and pat_dict is None:
+        if pat and not (isinstance(repl, str) or callable(repl)):
             raise TypeError("repl must be a string or callable")
 
         is_compiled_re = is_re(pat)
@@ -1557,9 +1563,9 @@ def replace(
         if case is None:
             case = True
 
-        if pat_dict:
+        if repl_kwargs:
             res_output = self._data
-            for key, value in pat_dict.items():
+            for key, value in repl_kwargs.items():
                 result = res_output.array._str_replace(
                     key, str(value), n=n, case=case, flags=flags, regex=regex
                 )

pandas/tests/strings/test_find_replace.py

@@ -354,27 +354,29 @@ def test_endswith_nullable_string_dtype(nullable_string_dtype, na):
 # --------------------------------------------------------------------------------------
 # str.replace
 # --------------------------------------------------------------------------------------
-def test_replace_dict_invalid(any_string_dtype):
-    # New replace behavior introduced in #51914
-    msg = "Cannot replace a string without specifying a string to be modified."
+@pytest.mark.parametrize(
+    "msg, kwargs",
+    [
+        ("Cannot replace a string without specifying a string to be modified.", {}),
+        (
+            "Cannot replace a string using both a pattern and <key : value> "
+            "combination.",
+            {"pat": "A*", "repl_kwargs": {"A": "a"}, "regex": True},
+        ),
+    ],
+)
+def test_replace_dict_invalid(any_string_dtype, msg, kwargs):
+    # GH 51914
     series = Series(data=["A", "B_junk", "C_gunk"], name="my_messy_col")
 
     with pytest.raises(ValueError, match=msg):
-        series.str.replace()
+        series.str.replace(**kwargs)
 
 
 def test_replace_dict(any_string_dtype):
-    # GH 51914
-    series = Series(data=["A", "B_junk", "C_gunk"], name="my_messy_col")
-    new_series1 = series.str.replace(pat_dict={"_gunk": "_junk"})
-    expected1 = Series(data=["A", "B_junk", "C_junk"], name="my_messy_col")
-    tm.assert_series_equal(new_series1, expected1)
-
-
-def test_replace_multi_dict(any_string_dtype):
     # GH 51914
     series = Series(data=["A", "B", "C"], name="my_messy_col")
-    new_series = series.str.replace(pat_dict={"A": "a", "B": "b"})
+    new_series = series.str.replace(repl_kwargs={"A": "a", "B": "b"})
     expected = Series(data=["a", "b", "C"], name="my_messy_col")
     tm.assert_series_equal(new_series, expected)