More unit test for attributes across thread clone

Author: leonerd

ext/XS-APItest/t/lexicalattributes.t

@@ -2,6 +2,7 @@ use v5.40;
 
 use Test::More;
 use XS::APItest;
+use Config ();
 
 our %ATTRIBUTES_APPLIED;
 
@@ -53,4 +54,13 @@ BEGIN {
         ':red attribute applied to lexical hash' );
 }
 
+# Attribute definitions survive thread cloning
+# (this is mostly a test of the underlying SVt_INTERNAL implementation)
+SKIP: {
+    last SKIP unless $Config::Config{usethreads};
+
+    require threads;
+    threads->create( sub { return 123 } )->join;
+}
+
 done_testing;