[Python-checkins] gh-107905: Test raising `__value__` for `TypeAliasType` (#107997)

[JelleZijlstra]

https://github.com/python/cpython/commit/13104f3b7412dce9bf7cfd09bf2d6dad1f3cc2ed
commit: 13104f3b7412dce9bf7cfd09bf2d6dad1f3cc2ed
branch: main
author: Nikita Sobolev <mail at sobolevn.me>
committer: JelleZijlstra <jelle.zijlstra at gmail.com>
date: 2023-08-21T13:52:37Z
summary:

gh-107905: Test raising `__value__` for `TypeAliasType` (#107997)

files:
M Lib/test/test_type_aliases.py

diff --git a/Lib/test/test_type_aliases.py b/Lib/test/test_type_aliases.py
index 0ce97f57de686..8f0a998e1f3dc 100644
--- a/Lib/test/test_type_aliases.py
+++ b/Lib/test/test_type_aliases.py
@@ -168,6 +168,24 @@ def test_recursive_repr(self):
         self.assertEqual(repr(GenericRecursive[GenericRecursive[int]]),
                          "GenericRecursive[GenericRecursive[int]]")
 
+    def test_raising(self):
+        type MissingName = list[_My_X]
+        with self.assertRaisesRegex(
+            NameError,
+            "cannot access free variable '_My_X' where it is not associated with a value",
+        ):
+            MissingName.__value__
+        _My_X = int
+        self.assertEqual(MissingName.__value__, list[int])
+        del _My_X
+        # Cache should still work:
+        self.assertEqual(MissingName.__value__, list[int])
+
+        # Explicit exception:
+        type ExprException = 1 / 0
+        with self.assertRaises(ZeroDivisionError):
+            ExprException.__value__
+
 
 class TypeAliasConstructorTest(unittest.TestCase):
     def test_basic(self):