ns_lib: new keyword 'Get Vnf Id'

Change-Id: Iaa0139048caff26e0f2325ec18dca874321c62c4
Signed-off-by: aguilarherna <daguilarh@indra.es>
diff --git a/robot-systest/lib/ns_lib.robot b/robot-systest/lib/ns_lib.robot
index d0b9d53..57eb6f5 100644
--- a/robot-systest/lib/ns_lib.robot
+++ b/robot-systest/lib/ns_lib.robot
@@ -57,6 +57,17 @@
     [Return]  ${stdout}
 
 
+Get Vnf Id
+    [Arguments]   ${ns_id}   ${vnf_member_index}
+
+    Should Not Be Empty   ${ns_id}
+    Should Not Be Empty   ${vnf_member_index}
+    ${rc}   ${stdout}=   Run and Return RC and Output   osm vnf-list --filter member-vnf-index-ref=${vnf_member_index} | grep ${ns_id} | awk '{print $2}' 2>&1
+    log   ${stdout}
+    Should Be Equal As Integers   ${rc}   ${success_return_code}
+    [Return]  ${stdout}
+
+
 Get Ns Vnf List
     [Arguments]   ${ns_id}