TST: Fixed PEP 8 warnings pandas-dev#25581

Author: KingOfTheShow69

pandas/tests/groupby/aggregate/test_aggregate.py

@@ -1414,12 +1414,13 @@ def test_multi_axis_1_raises(func):
     with pytest.raises(NotImplementedError, match="axis other than 0 is not supported"):
         gb.agg(func)
 
+
 def test_agg_of_list():
     # GH#25581
-    df1 = pd.DataFrame([[20, 'A'], [20, 'B'], [30, 'C']])
+    df1 = pd.DataFrame([[20, "A"], [20, "B"], [30, "C"]])
     result = df1.groupby(0).agg(pd.Series.mode)
 
-    expected = pd.DataFrame({0: [20, 30], 1: [['A', 'B'], 'C']})
+    expected = pd.DataFrame({0: [20, 30], 1: [["A", "B"], "C"]})
     expected = expected.set_index(0)
 
     tm.assert_frame_equal(result, expected)