Changed string formatting to fstring

pandas/tests/resample/test_datetime_index.py

@@ -146,9 +146,7 @@ def test_resample_basic_grouper(series):
 def test_resample_string_kwargs(series, keyword, value):
     # see gh-19303
     # Check that wrong keyword argument strings raise an error
-    msg = "Unsupported value {value} for `{keyword}`".format(
-        value=value, keyword=keyword
-    )
+    msg = f"Unsupported value {value} for `{keyword}`"
     with pytest.raises(ValueError, match=msg):
         series.resample("5min", **({keyword: value}))
 

pandas/tests/resample/test_time_grouper.py

@@ -89,7 +89,7 @@ def test_fails_on_no_datetime_index(name, func):
 
     msg = (
         "Only valid with DatetimeIndex, TimedeltaIndex "
-        "or PeriodIndex, but got an instance of '{}'".format(name)
+        f"or PeriodIndex, but got an instance of '{name}'"
     )
     with pytest.raises(TypeError, match=msg):
         df.groupby(Grouper(freq="D"))

pandas/tests/tseries/offsets/common.py

@@ -13,18 +13,14 @@ def assert_offset_equal(offset, base, expected):
         assert actual_apply == expected
     except AssertionError:
         raise AssertionError(
-            "\nExpected: {expected}\nActual: {actual}\nFor Offset: {offset})"
-            "\nAt Date: {base}".format(
-                expected=expected, actual=actual, offset=offset, base=base
-            )
+            f"\nExpected: {expected}\nActual: {actual}\nFor Offset: {offset})"
+            f"\nAt Date: {base}"
         )
 
 
 def assert_onOffset(offset, date, expected):
     actual = offset.onOffset(date)
     assert actual == expected, (
-        "\nExpected: {expected}\nActual: {actual}\nFor Offset: {offset})"
-        "\nAt Date: {date}".format(
-            expected=expected, actual=actual, offset=offset, date=date
-        )
+        f"\nExpected: {expected}\nActual: {actual}\nFor Offset: {offset})"
+        f"\nAt Date: {date}"
     )