Fixed #38419 - BUG: set_index screws up the dtypes on empty DataFrames

Author: jordi-crespo

pandas/tests/frame/methods/test_set_index.py

@@ -56,8 +56,8 @@ def test_set_index_empty_dataframe(self):
         if df.empty:
             df = DataFrame(columns=list(df.columns.values))
 
-        expected = df.set_index(['a', 'b'])
-        assert (df.loc[:, ['a', 'b']].dtypes == expected.index.to_frame().dtypes).all()
+        expected = df.set_index(["a", "b"])
+        assert (df.loc[:, ["a", "b"]].dtypes == expected.index.to_frame().dtypes).all()
 
     def test_set_index_multiindexcolumns(self):
         columns = MultiIndex.from_tuples([("foo", 1), ("foo", 2), ("bar", 1)])