From 00b3ece69d4aa1a5479465e88e4051f8abd10738 Mon Sep 17 00:00:00 2001
From: Jim Crist-Harif <jcristharif@gmail.com>
Date: Thu, 18 Jan 2024 11:14:42 -0600
Subject: [PATCH] fix(api): deferred values are not truthy

---
 ibis/common/deferred.py            | 5 +++++
 ibis/common/tests/test_deferred.py | 8 ++++++++
 2 files changed, 13 insertions(+)

diff --git a/ibis/common/deferred.py b/ibis/common/deferred.py
index 03bf7eb3b948..17290ba4aaa6 100644
--- a/ibis/common/deferred.py
+++ b/ibis/common/deferred.py
@@ -97,6 +97,11 @@ def __getattr__(self, name):
     def __iter__(self):
         raise TypeError(f"{self.__class__.__name__!r} object is not iterable")
 
+    def __bool__(self):
+        raise TypeError(
+            f"The truth value of {self.__class__.__name__} objects is not defined"
+        )
+
     def __getitem__(self, name):
         return Deferred(Item(self, name))
 
diff --git a/ibis/common/tests/test_deferred.py b/ibis/common/tests/test_deferred.py
index df6a0a343be8..616eebb47097 100644
--- a/ibis/common/tests/test_deferred.py
+++ b/ibis/common/tests/test_deferred.py
@@ -501,6 +501,14 @@ def test_deferred_is_not_iterable(obj):
         next(obj)
 
 
+@pytest.mark.parametrize("obj", [_, _.a, _.a.b[0]])
+def test_deferred_is_not_truthy(obj):
+    with pytest.raises(
+        TypeError, match="The truth value of Deferred objects is not defined"
+    ):
+        bool(obj)
+
+
 def test_deferrable(table):
     @deferrable
     def f(a, b, c=3):