Persisting a list element to a parent list (ep2)

Post List Element does not allow for create List Element, only appends onto existing node as children

-Add a check in saveListElements to see if the parent xpath is a root path ("/").If root node store list element as top node. Else add passed list element to parent xpath node.
-Add test for scenario for above
-Add test scenario Saving list element data fragment under Root node
-Add Integration Tests Add and Delete top-level list (element) data nodes with root node
-Update bookstore model with TopLevelList datanode

Issue-ID: CPS-1586
Change-Id: Iaa7f59fbeebb03703626132c6d5c2afde0e7ab4b
Signed-off-by: Rudrangi Anupriya <ra00745022@techmahindra.com>
diff --git a/cps-service/src/test/resources/bookstore.yang b/cps-service/src/test/resources/bookstore.yang
index 2179fb9..b7a52e2 100644
--- a/cps-service/src/test/resources/bookstore.yang
+++ b/cps-service/src/test/resources/bookstore.yang
@@ -15,6 +15,34 @@
         }
     }
 
+    list invoice {
+        key "ProductID";
+        leaf ProductID {
+            type uint64;
+            mandatory "true";
+            description
+            "Unique product ID. Example: 001";
+        }
+        leaf ProductName {
+            type string;
+            mandatory "true";
+            description
+            "Name of the Product";
+        }
+        leaf price {
+            type uint64;
+            mandatory "true";
+            description
+            "Price of book";
+        }
+        leaf stock {
+            type boolean;
+            default "false";
+            description
+            "Book in stock or not. Example value: true";
+        }
+    }
+
     container bookstore {
 
         leaf bookstore-name {