Fix issue with indirect return for C++ member function w/no args

diff --git a/tests/test.rs b/tests/test.rs
index 91bd25e..836e2d3 100644
--- a/tests/test.rs
+++ b/tests/test.rs
@@ -157,7 +157,9 @@
     assert_eq!(2021, unique_ptr.set(2021));
     assert_eq!(2021, unique_ptr.get());
     assert_eq!(old_value, unique_ptr.set2(old_value));
-    assert_eq!(old_value, unique_ptr.get2())
+    assert_eq!(old_value, unique_ptr.get2());
+    assert_eq!(Ok(2022), unique_ptr.set_succeed(2022));
+    assert!(unique_ptr.get_fail().is_err());
 }
 
 #[test]