From 50cba80b21054dec3ee42d00ea4a84d86c36c2a7 Mon Sep 17 00:00:00 2001
From: Filipe Brandenburger <filipe@hudson-trading.com>
Date: Thu, 14 Nov 2024 23:18:58 -0500
Subject: [PATCH] Make attrs work with a converter instance that does not
 evaluate True

---
 src/attr/_make.py        |  2 +-
 tests/test_converters.py | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/attr/_make.py b/src/attr/_make.py
index e0cd9e0b..13cc9943 100644
--- a/src/attr/_make.py
+++ b/src/attr/_make.py
@@ -2021,7 +2021,7 @@ def _attrs_to_init_script(
         has_factory = isinstance(a.default, Factory)
         maybe_self = "self" if has_factory and a.default.takes_self else ""
 
-        if a.converter and not isinstance(a.converter, Converter):
+        if a.converter is not None and not isinstance(a.converter, Converter):
             converter = Converter(a.converter)
         else:
             converter = a.converter
diff --git a/tests/test_converters.py b/tests/test_converters.py
index d4aca430..4747f13c 100644
--- a/tests/test_converters.py
+++ b/tests/test_converters.py
@@ -112,6 +112,25 @@ def wrapped(_, __, ___) -> float:
         assert float is c.__call__.__annotations__["return"]
         assert None is c2.__call__.__annotations__.get("return")
 
+    def test_falsey_converter(self):
+        """
+        Passing a false-y instance still produces a valid converter.
+        """
+
+        class MyConv:
+            def __bool__(self):
+                return False
+
+            def __call__(self, value):
+                return value * 2
+
+        @attr.s
+        class C:
+            a = attrib(converter=MyConv())
+
+        c = C(21)
+        assert 42 == c.a
+
 
 class TestOptional:
     """