From cdd0e40255d39c22f9c6a93ca3429667ca3d00a2 Mon Sep 17 00:00:00 2001
From: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
Date: Mon, 9 Dec 2024 15:32:00 +0100
Subject: [PATCH] Add regression test for isinstance narrowing

---
 test-data/unit/check-isinstance.test | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/test-data/unit/check-isinstance.test b/test-data/unit/check-isinstance.test
index 99bd62765b11..4ad128914c4e 100644
--- a/test-data/unit/check-isinstance.test
+++ b/test-data/unit/check-isinstance.test
@@ -2917,3 +2917,18 @@ if hasattr(mod, "y"):
 [file mod.py]
 def __getattr__(attr: str) -> str: ...
 [builtins fixtures/module.pyi]
+
+[case testTypeIsntLostAfterNarrowing]
+from typing import Any
+
+var: Any
+reveal_type(var)  # N: Revealed type is "Any"
+assert isinstance(var, (bool, str))
+reveal_type(var)  # N: Revealed type is "Union[builtins.bool, builtins.str]"
+
+if isinstance(var, bool):
+    reveal_type(var)  # N: Revealed type is "builtins.bool"
+
+# Type of var shouldn't fall back to Any
+reveal_type(var)  # N: Revealed type is "Union[builtins.bool, builtins.str]"
+[builtins fixtures/isinstance.pyi]