updated the tests for this case

Author: krototype

spec/core/GraphRequestUtil.ts

@@ -61,10 +61,15 @@ describe("GraphRequestUtil.ts", () => {
 			node2.link = node1;
 			try {
 				serializeContent(node1);
-				throw new Error("Something wrong with the serialize content, it should stringify cyclic referenced objects");
+				throw new Error("Something wrong with the serialize content, it should not stringify cyclic referenced objects");
 			} catch (error) {
 				assert.equal(error.message, "Unable to stringify the content");
 			}
 		});
+
+		it("Should return undefined for the case of undefined content value", () => {
+			const val = undefined;
+			assert.equal(serializeContent(val), undefined);
+		});
 	});
 });