YANG sub module linking + unsupported yang construct + defect fix

Change-Id: I224c8c14ee2111f6844278cb540c48651544f59b
diff --git a/src/test/java/org/onosproject/yangutils/parser/impl/listeners/EnumListenerTest.java b/src/test/java/org/onosproject/yangutils/parser/impl/listeners/EnumListenerTest.java
index 6f13667..a78c65f 100644
--- a/src/test/java/org/onosproject/yangutils/parser/impl/listeners/EnumListenerTest.java
+++ b/src/test/java/org/onosproject/yangutils/parser/impl/listeners/EnumListenerTest.java
@@ -18,7 +18,10 @@
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.Is.is;
+
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.onosproject.yangutils.datamodel.YangDataTypes;
 import org.onosproject.yangutils.datamodel.YangEnum;
 import org.onosproject.yangutils.datamodel.YangEnumeration;
@@ -38,6 +41,9 @@
  */
 public class EnumListenerTest {
 
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
     private final YangUtilsParserManager manager = new YangUtilsParserManager();
 
     /**
@@ -84,7 +90,28 @@
      */
     @Test(expected = ParserException.class)
     public void processEnumWithDuplicateName() throws IOException, ParserException {
-
         YangNode node = manager.getDataModel("src/test/resources/EnumWithDuplicateName.yang");
     }
+
+    /**
+     * Checks enum boundary value.
+     */
+    @Test
+    public void processEnumBoundaryValue() throws IOException, ParserException {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("YANG file error : value value 21474836472147483647 is not valid.");
+        YangNode node = manager.getDataModel("src/test/resources/EnumBoundaryValue.yang");
+    }
+
+    /**
+     * Checks whether exception is thrown if value is not specified following max enum value.
+     */
+    @Test
+    public void processEnumMaxNextValue() throws IOException, ParserException {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("YANG file error : "
+                + "An enum value MUST be specified for enum substatements following the one"
+                + "with the current highest value");
+        YangNode node = manager.getDataModel("src/test/resources/EnumMaxNextValue.yang");
+    }
 }