UserManager: Fix unit test cases

User_mgr and ldap_mapper testcases are failing with D-bus errors.
This commit fixes both testcases by using mocked sdbus.

Signed-off-by: Ravi Teja <raviteja28031990@gmail.com>
Change-Id: I3fcabeb1781c938affa11a1370b107d628242374
diff --git a/test/ldap_mapper_test.cpp b/test/ldap_mapper_test.cpp
index 9853c85..b3c1a4f 100644
--- a/test/ldap_mapper_test.cpp
+++ b/test/ldap_mapper_test.cpp
@@ -8,6 +8,7 @@
 #include <xyz/openbmc_project/Common/error.hpp>
 #include <xyz/openbmc_project/User/Common/error.hpp>
 #include "config.h"
+#include <sdbusplus/test/sdbus_mock.hpp>
 
 namespace phosphor
 {
@@ -19,7 +20,9 @@
 class TestSerialization : public testing::Test
 {
   public:
-    TestSerialization() : bus(sdbusplus::bus::new_default())
+    sdbusplus::SdBusMock sdbusMock;
+
+    TestSerialization() : bus(sdbusplus::get_mocked_new(&sdbusMock))
     {
     }