Defect fix for YANG revision

Change-Id: I6af5e82122629ea69c40b4fc3159bc7712d8293d
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListenerTest.java
index c3028de..26d79f4 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListenerTest.java
@@ -26,6 +26,7 @@
 import java.io.IOException;
 
 import static org.hamcrest.core.Is.is;
+import static org.hamcrest.core.IsNull.notNullValue;
 import static org.junit.Assert.assertThat;
 
 /**
@@ -107,6 +108,8 @@
         assertThat(yangNode.getBelongsTo().getBelongsToModuleName(), is("ONOS"));
         // Checks for the version value in data model tree.
         assertThat(yangNode.getBelongsTo().getPrefix(), is("On1"));
+        //Checks the revision with current date is created for empty revision statement.
+        assertThat(((YangSubModule) node).getRevision().getRevDate(),   notNullValue());
     }
 
     /**