From c5b8e3ab8c180f7b4253d3d315b1c7828b94556e Mon Sep 17 00:00:00 2001
From: Phillip Cloud <417981+cpcloud@users.noreply.github.com>
Date: Mon, 26 Aug 2024 11:04:57 -0400
Subject: [PATCH] test: handle empty sequences to `_to_selector` and test empty
 `c()`

---
 ibis/selectors.py                 |  2 ++
 ibis/tests/expr/test_selectors.py | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/ibis/selectors.py b/ibis/selectors.py
index 8d5b516c0e8f..14d80ed0f4cb 100644
--- a/ibis/selectors.py
+++ b/ibis/selectors.py
@@ -720,5 +720,7 @@ def _to_selector(
         raise exc.IbisInputError(
             f"Cannot compose {obj.__class__.__name__} with other selectors"
         )
+    elif not obj:
+        return none()
     else:
         return any_of(*obj)
diff --git a/ibis/tests/expr/test_selectors.py b/ibis/tests/expr/test_selectors.py
index 5c53f46bb9ae..c254ab3f8886 100644
--- a/ibis/tests/expr/test_selectors.py
+++ b/ibis/tests/expr/test_selectors.py
@@ -531,19 +531,22 @@ def test_methods(penguins):
     assert [col.get_name() for col in bound] == penguins.columns
 
 
-def test_none_selector(penguins):
-    assert not s.none().expand(penguins)
-    assert not s.none().expand_names(penguins)
+@pytest.mark.parametrize("sel", [s.none(), s.c(), []])
+def test_none_selector(penguins, sel):
+    sel = s._to_selector(sel)
 
-    assert list((s.none() | s.c("year")).expand_names(penguins)) == ["year"]
+    assert not sel.expand(penguins)
+    assert not sel.expand_names(penguins)
+
+    assert list((sel | s.c("year")).expand_names(penguins)) == ["year"]
 
     with pytest.raises(exc.IbisError):
-        penguins.select(s.none())
+        penguins.select(sel)
 
     with pytest.raises(exc.IbisError):
-        penguins.select(s.none() & s.c("year"))
+        penguins.select(sel & s.c("year"))
 
-    assert penguins.select(s.none() | s.c("year")).equals(penguins.select("year"))
+    assert penguins.select(sel | s.c("year")).equals(penguins.select("year"))
 
 
 def test_invalid_composition():