Test wide mode mutation with integer column names; reword comment

Author: cpruijsen

plotly/express/_core.py

@@ -1687,7 +1687,7 @@ def build_dataframe(args, constructor):
             args["wide_variable"] = args["y"] if wide_y else args["x"]
             if df_provided and is_pd_like and args["wide_variable"] is columns:
                 var_name = columns.name
-            # copy into a new list so that the list provided by the user for
+            # copy into a new list so that the object passed by the user for
             # x or y is not mutated when wide_variable's entries are replaced
             args["wide_variable"] = list(args["wide_variable"])
             if var_name in [None, "value", "index"] or (

tests/test_optional/test_px/test_px_wide.py

@@ -894,12 +894,9 @@ def test_no_pd_perf_warning():
 
 def test_wide_mode_does_not_mutate_x_or_y():
     # https://github.com/plotly/plotly.py/issues/4117
-    df = pd.DataFrame(dict(a=[1, 2, 3], b=[4, 5, 6], c=[7, 8, 9]))
+    # integer column names, as in the issue: string names are a no-op here
+    df = pd.DataFrame([[1, 4, 7], [2, 5, 8], [3, 6, 9]])
     for arg in ["x", "y"]:
-        cols = ["a", "b"]
+        cols = [0, 1]
         px.bar(df, **{arg: cols})
-        assert cols == ["a", "b"]
-    cols = [0, 1]
-    df_int = pd.DataFrame([[1, 2], [3, 4]])
-    px.histogram(df_int, x=cols)
-    assert cols == [0, 1]
+        assert cols == [0, 1]