CLN: Don't intercept NotImplementedError in _cython_transform (#49742)

Author: rhshadrach

pandas/core/groupby/generic.py

@@ -1357,13 +1357,9 @@ def arr_func(bvalues: ArrayLike) -> ArrayLike:
 
         # We could use `mgr.apply` here and not have to set_axis, but
         #  we would have to do shape gymnastics for ArrayManager compat
-        try:
-            res_mgr = mgr.grouped_reduce(
-                arr_func, ignore_failures=numeric_only is lib.no_default
-            )
-        except NotImplementedError as err:
-            # For NotImplementedError, args[0] is the error message
-            raise TypeError(err.args[0]) from err
+        res_mgr = mgr.grouped_reduce(
+            arr_func, ignore_failures=numeric_only is lib.no_default
+        )
         res_mgr.set_axis(1, mgr.axes[1])
 
         if len(res_mgr) < orig_mgr_len:

pandas/tests/groupby/test_function.py

@@ -250,6 +250,10 @@ def test_cummin_cummax(self, df, method):
     def _check(self, df, method, expected_columns, expected_columns_numeric):
         gb = df.groupby("group")
 
+        # object dtypes for transformations are not implemented in Cython and
+        # have no Python fallback
+        exception = NotImplementedError if method.startswith("cum") else TypeError
+
         if method in ("min", "max", "cummin", "cummax"):
             # The methods default to numeric_only=False and raise TypeError
             msg = "|".join(
@@ -258,7 +262,7 @@ def _check(self, df, method, expected_columns, expected_columns_numeric):
                     "function is not implemented for this dtype",
                 ]
             )
-            with pytest.raises(TypeError, match=msg):
+            with pytest.raises(exception, match=msg):
                 getattr(gb, method)()
         else:
             result = getattr(gb, method)()
@@ -274,7 +278,7 @@ def _check(self, df, method, expected_columns, expected_columns_numeric):
                     "function is not implemented for this dtype",
                 ]
             )
-            with pytest.raises(TypeError, match=msg):
+            with pytest.raises(exception, match=msg):
                 getattr(gb, method)(numeric_only=False)
         else:
             result = getattr(gb, method)(numeric_only=False)
@@ -1436,6 +1440,11 @@ def test_deprecate_numeric_only(
     elif has_arg or kernel in ("idxmax", "idxmin"):
         assert numeric_only is not True
         # kernels that are successful on any dtype were above; this will fail
+
+        # object dtypes for transformations are not implemented in Cython and
+        # have no Python fallback
+        exception = NotImplementedError if kernel.startswith("cum") else TypeError
+
         msg = "|".join(
             [
                 "not allowed for this dtype",
@@ -1447,7 +1456,7 @@ def test_deprecate_numeric_only(
                 "function is not implemented for this dtype",
             ]
         )
-        with pytest.raises(TypeError, match=msg):
+        with pytest.raises(exception, match=msg):
             method(*args, **kwargs)
     elif not has_arg and numeric_only is not lib.no_default:
         with pytest.raises(