test(python): Add test on selecting Enum columns (#14628)

py-polars/tests/unit/datatypes/test_enum.py

@@ -9,7 +9,7 @@
 
 import polars as pl
 from polars import StringCache
-from polars.testing import assert_series_equal
+from polars.testing import assert_frame_equal, assert_series_equal
 
 
 def test_enum_creation() -> None:
@@ -402,3 +402,22 @@ def test_enum_cast_from_other_integer_dtype_oob() -> None:
         pl.ComputeError, match="conversion from `u64` to `u32` failed in column"
     ):
         series.cast(enum_dtype)
+
+
+def test_enum_creating_col_expr() -> None:
+    df = pl.DataFrame(
+        {
+            "col1": ["a", "b", "c"],
+            "col2": ["d", "e", "f"],
+            "col3": ["g", "h", "i"],
+        },
+        schema={
+            "col1": pl.Enum(["a", "b", "c"]),
+            "col2": pl.Categorical(),
+            "col3": pl.Enum(["g", "h", "i"]),
+        },
+    )
+
+    out = df.select(pl.col(pl.Enum))
+    expected = df.select("col1", "col3")
+    assert_frame_equal(out, expected)