Add failing test for __qualname__ type checking (fixes #20821)

python · BHUVANSH855 · Apr 13, 2026 · Apr 13, 2026 · Apr 13, 2026 · Apr 13, 2026
commit cca081720fb63a57d83985e2f86948f11f7e8fbf
diff --git a/test-data/unit/check-classes.test b/test-data/unit/check-classes.test
@@ -9412,3 +9412,9 @@ from typ import NT
 def f() -> NT:
     return NT(x='')
 [builtins fixtures/tuple.pyi]
+
+[case test_qualname_must_be_str]
+class X:
+    __qualname__ = 5
+[out]
+error: "__qualname__" must be str