Defect fix for YANG revision

Change-Id: I6af5e82122629ea69c40b4fc3159bc7712d8293d
diff --git a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListenerTest.java b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListenerTest.java
index 8226442..2812a36 100644
--- a/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListenerTest.java
+++ b/utils/yangutils/src/test/java/org/onosproject/yangutils/parser/impl/listeners/RevisionListenerTest.java
@@ -25,6 +25,7 @@
 import java.io.IOException;
 
 import static org.hamcrest.core.Is.is;
+import static org.hamcrest.core.IsNull.notNullValue;
 import static org.junit.Assert.assertThat;
 
 /**
@@ -64,4 +65,14 @@
 
         YangNode node = manager.getDataModel("src/test/resources/RevisionInValidOrder.yang");
     }
+
+    /**
+     * Checks the revision with current date is created for empty revision statement.
+     */
+    @Test
+    public void processWithoutRevision() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionAbsence.yang");
+        assertThat(((YangModule) node).getRevision().getRevDate(),   notNullValue());
+    }
 }
\ No newline at end of file
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());
     }
 
     /**
diff --git a/utils/yangutils/src/test/resources/RevisionAbsence.yang b/utils/yangutils/src/test/resources/RevisionAbsence.yang
new file mode 100644
index 0000000..eb1d1d9
--- /dev/null
+++ b/utils/yangutils/src/test/resources/RevisionAbsence.yang
@@ -0,0 +1,5 @@
+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+}