BUG/TST/DOC: added finalize to melt, GH28283 (#46648)

Author: edwhuang23

doc/source/whatsnew/v1.5.0.rst

@@ -625,6 +625,7 @@ Styler
 
 Metadata
 ^^^^^^^^
+- Fixed metadata propagation in :meth:`DataFrame.melt` (:issue:`28283`)
 - Fixed metadata propagation in :meth:`DataFrame.explode` (:issue:`28283`)
 -
 

pandas/core/frame.py

@@ -8717,7 +8717,7 @@ def melt(
             value_name=value_name,
             col_level=col_level,
             ignore_index=ignore_index,
-        )
+        ).__finalize__(self, method="melt")
 
     # ----------------------------------------------------------------------
     # Time series-related

pandas/tests/generic/test_finalize.py

@@ -156,13 +156,10 @@
     (pd.DataFrame, frame_data, operator.methodcaller("stack")),
     (pd.DataFrame, frame_data, operator.methodcaller("explode", "A")),
     (pd.DataFrame, frame_mi_data, operator.methodcaller("unstack")),
-    pytest.param(
-        (
-            pd.DataFrame,
-            ({"A": ["a", "b", "c"], "B": [1, 3, 5], "C": [2, 4, 6]},),
-            operator.methodcaller("melt", id_vars=["A"], value_vars=["B"]),
-        ),
-        marks=not_implemented_mark,
+    (
+        pd.DataFrame,
+        ({"A": ["a", "b", "c"], "B": [1, 3, 5], "C": [2, 4, 6]},),
+        operator.methodcaller("melt", id_vars=["A"], value_vars=["B"]),
     ),
     pytest.param(
         (pd.DataFrame, frame_data, operator.methodcaller("applymap", lambda x: x))