utils: Retrieval of managed objects of DBUS

This commit implements functionality to retrieve the managed object of a
specific DBUS service on a particular path.  Additionally implements a
function template for inventory objects which efficiently enables
retrieval of managed object for Inventory Manager.

Tested: Added unit test cases for checking the return value.

Change-Id: Ide652f843db1623bdacebf3e269e03895bbb7f1a
Signed-off-by: Riya Dixit <riyadixitagra@gmail.com>
diff --git a/common/test/mocked_utils.hpp b/common/test/mocked_utils.hpp
index 71bc6e7..e42677c 100644
--- a/common/test/mocked_utils.hpp
+++ b/common/test/mocked_utils.hpp
@@ -22,6 +22,35 @@
 } // namespace utils
 } // namespace pldm
 
+class GetManagedEmptyObject
+{
+  public:
+    static pldm::utils::ObjectValueTree getManagedObj(const char* /*service*/,
+                                                      const char* /*path*/)
+    {
+        return pldm::utils::ObjectValueTree{};
+    }
+};
+
+class GetManagedObject
+{
+  public:
+    static pldm::utils::ObjectValueTree getManagedObj(const char* /*service*/,
+                                                      const char* /*path*/)
+    {
+        return pldm::utils::ObjectValueTree{
+            {sdbusplus::message::object_path("/foo/bar"),
+             {{"foo.bar",
+               {{"Functional", true},
+                {"Enabled", true},
+                {"PrettyName", "System"},
+                {"Present", true},
+                {"SerialNumber", "abc123z"},
+                {"Model", "1234 - 00Z"},
+                {"SubModel", "S0"}}}}}};
+    }
+};
+
 class MockdBusHandler : public pldm::utils::DBusHandler
 {
   public: