Re-enable unit test

Unit test were broken after sd bus calls started throwing exception,
In this repo we start the systemd-networkd with the use of sd bus
calls, which throws exception and it was not handled in the test case.

This commit fixes the problem by mocking the network manager which
mock the functionality of function which makes the sdbus call.

Change-Id: I5b60a2117a661cffa36200415ca611b85dd2fda1
Signed-off-by: Ratan Gupta <ratagupt@linux.vnet.ibm.com>
diff --git a/test/test_ethernet_interface.cpp b/test/test_ethernet_interface.cpp
index 1b284a2..9e611a6 100644
--- a/test/test_ethernet_interface.cpp
+++ b/test/test_ethernet_interface.cpp
@@ -1,7 +1,7 @@
 #include "config_parser.hpp"
 #include "ipaddress.hpp"
+#include "mock_network_manager.hpp"
 #include "mock_syscall.hpp"
-#include "network_manager.hpp"
 
 #include <arpa/inet.h>
 #include <net/if.h>
@@ -23,7 +23,7 @@
 {
   public:
     sdbusplus::bus::bus bus;
-    Manager manager;
+    MockManager manager;
     EthernetInterface interface;
     std::string confDir;
     TestEthernetInterface() :
@@ -188,6 +188,7 @@
 TEST_F(TestEthernetInterface, addNTPServers)
 {
     ServerList servers = {"10.1.1.1", "10.2.2.2", "10.3.3.3"};
+    EXPECT_CALL(manager, restartSystemdUnit(networkdService)).Times(1);
     interface.nTPServers(servers);
     fs::path filePath = confDir;
     filePath /= "00-bmc-test0.network";