Fix test

pandas/tests/groupby/test_groupby_shift_diff.py

@@ -246,6 +246,9 @@ def test_group_shift_with_multiple_periods_and_both_fill_and_freq_fails():
         {"a": [1, 2, 3, 4, 5], "b": [True, True, False, False, True]},
         index=date_range("1/1/2000", periods=5, freq="H"),
     )
-    msg = r"Cannot pass both 'freq' and 'fill_value' to.*"
-    with pytest.raises(ValueError, match=msg):
+    msg = (
+        "Passing a 'freq' together with a 'fill_value' silently ignores the "
+        "fill_value"
+    )
+    with tm.assert_produces_warning(FutureWarning, match=msg):
         df.groupby("b")[["a"]].shift([1, 2], fill_value=1, freq="H")