code sample for pandas-dev#46317

Author: simonjayhawkins

bisect/46317.py

@@ -0,0 +1,18 @@
+# BUG: Difference in CSV roundtrip between 1.3.5 and 1.4.1 #46317
+
+import pandas as pd
+
+print(pd.__version__)
+
+df = pd.DataFrame(
+    index=pd.MultiIndex.from_tuples([], names=["a", "b", "c"]), columns=["x"]
+)
+df.loc[(1, 2, 3)] = "bar"
+print(df)
+
+expected = pd.DataFrame(
+    ["bar"],
+    index=pd.MultiIndex.from_tuples([(1, 2, 3)], names=["a", "b", "c"]),
+    columns=["x"],
+)
+pd.testing.assert_frame_equal(df, expected)