adding test_promotion_of_disowned_to_shared

tests/test_variant_unique_shared.cpp

@@ -40,8 +40,13 @@ TEST_SUBMODULE(variant_unique_shared, m) {
                  v.get_unique();
                  v.get_unique();
                  return;
                  return;
              })
              })
-        .def("get_shared", [](vptr<double> &v) {
-            v.get_shared();
+        .def("get_shared",
+             [](vptr<double> &v) {
+                 v.get_shared();
+                 return;
+             })
+        .def("disown_unique", [](vptr<double> &v) {
+            v.get_unique().reset();
             return;
             return;
         });
         });
 }
 }

tests/test_variant_unique_shared.py

@@ -48,3 +48,14 @@ def test_shared_from_birth():
         v.get_unique()
         v.get_unique()
     assert str(exc_info.value) == "get_unique failure."
     assert str(exc_info.value) == "get_unique failure."
     v.get_shared()  # Still works.
     v.get_shared()  # Still works.
+
+
+def test_promotion_of_disowned_to_shared():
+    v = m.from_unique()
+    assert v.get_value() == 5
+    v.disown_unique()
+    assert v.ownership_type() == 0
+    assert v.get_value() == -1
+    v.get_shared()  # Promotion of disowned to shared_ptr.
+    assert v.ownership_type() == 1
+    assert v.get_value() == -1