config ang key validation and UT for the same

Change-Id: I507740fc9da3f3da5fb3c88a7414f87db6251c5b
diff --git a/src/test/resources/ConfigFalseNoKey.yang b/src/test/resources/ConfigFalseNoKey.yang
new file mode 100644
index 0000000..66f141e
--- /dev/null
+++ b/src/test/resources/ConfigFalseNoKey.yang
@@ -0,0 +1,14 @@
+module Test {
+    yang-version 1;
+    namespace http://huawei.com;
+    prefix Ant;
+    list valid {
+        config false;
+        leaf invalid-interval {
+            type "string";
+            units "seconds";
+            status current;
+            reference "RFC 6020";
+        }
+    }
+}