Added new test case to SNMP-Alerts submenu

Changes:
    - Added test to configure SNMP manager with empty IP,
      negative IPand alphanumeric port and verify

Tested:
    - Ran successfully test_snmp_alerts_sub_menu.robot

Change-Id: I4a8be9c63e426d22e131216c1817a3b83a2d5e9d
Signed-off-by: Megha G N <Megha.G.N@ibm.com>
diff --git a/gui/gui_test/settings_menu/test_snmp_alerts_sub_menu.robot b/gui/gui_test/settings_menu/test_snmp_alerts_sub_menu.robot
index 1aca1ad..116c84f 100644
--- a/gui/gui_test/settings_menu/test_snmp_alerts_sub_menu.robot
+++ b/gui/gui_test/settings_menu/test_snmp_alerts_sub_menu.robot
@@ -115,8 +115,11 @@
     ${SNMP_MGR1_IP}     ${out_of_range_port}     ${invalid_port_error}
     ${SNMP_MGR1_IP}     ${alpha_port}            ${invalid_port_error}
     ${SNMP_MGR1_IP}     ${negative_port}         ${invalid_port_error}
+    ${SNMP_MGR1_IP}     ${alphanumeric_port}     ${invalid_port_error}
     ${out_of_range_ip}  ${NON_DEFAULT_PORT1}     ${invalid_destination_error}
     ${alpha_ip}         ${NON_DEFAULT_PORT1}     ${invalid_destination_error}
+    ${negative_ip}      ${NON_DEFAULT_PORT1}     ${invalid_destination_error}
+    ${empty_ip}         ${NON_DEFAULT_PORT1}     ${invalid_destination_error}
 
 
 Configure Multiple SNMP Managers On BMC Via GUI And Verify