CLN: GH29547 change string formatting with f-strings (6 files changed) (#34831)

Author: MatteoFelici

pandas/tests/io/parser/test_header.py

@@ -528,12 +528,11 @@ def test_multi_index_unnamed(all_parsers, index_col, columns):
             parser.read_csv(StringIO(data), header=header, index_col=index_col)
     else:
         result = parser.read_csv(StringIO(data), header=header, index_col=index_col)
-        template = "Unnamed: {i}_level_0"
         exp_columns = []
 
         for i, col in enumerate(columns):
             if not col:  # Unnamed.
-                col = template.format(i=i if index_col is None else i + 1)
+                col = f"Unnamed: {i if index_col is None else i + 1}_level_0"
 
             exp_columns.append(col)
 

pandas/tests/io/test_sql.py

@@ -1900,9 +1900,9 @@ class _TestMySQLAlchemy:
 
     @classmethod
     def connect(cls):
-        url = "mysql+{driver}://root@localhost/pandas_nosetest"
         return sqlalchemy.create_engine(
-            url.format(driver=cls.driver), connect_args=cls.connect_args
+            f"mysql+{cls.driver}://root@localhost/pandas_nosetest",
+            connect_args=cls.connect_args,
         )
 
     @classmethod
@@ -1969,8 +1969,9 @@ class _TestPostgreSQLAlchemy:
 
     @classmethod
     def connect(cls):
-        url = "postgresql+{driver}://postgres@localhost/pandas_nosetest"
-        return sqlalchemy.create_engine(url.format(driver=cls.driver))
+        return sqlalchemy.create_engine(
+            f"postgresql+{cls.driver}://postgres@localhost/pandas_nosetest"
+        )
 
     @classmethod
     def setup_driver(cls):

pandas/tests/reductions/test_reductions.py

@@ -349,11 +349,10 @@ def test_invalid_td64_reductions(self, opname):
 
         msg = "|".join(
             [
-                "reduction operation '{op}' not allowed for this dtype",
-                r"cannot perform {op} with type timedelta64\[ns\]",
+                f"reduction operation '{opname}' not allowed for this dtype",
+                rf"cannot perform {opname} with type timedelta64\[ns\]",
             ]
         )
-        msg = msg.format(op=opname)
 
         with pytest.raises(TypeError, match=msg):
             getattr(td, opname)()