[ONOS-3880, 3881] Yang Listener for Module and Sub-Module

Change-Id: Iee75c3e04af9b66ebc38acb3396aa4c54af5a268

@@ -130,7 +130,186 @@ public enum ParsableDataType {
     REVISION_DATA,
 
     /**
+     * Identifies the YANG revision date parsed data.
+     */
+    REVISION_DATE_DATA,
+
+    /**
      * Identifies the YANG namespace parsed data.
      */
-    NAMESPACE_DATA
+    NAMESPACE_DATA,
+
+    /**
+     * Identifies the YANG contact parsed data.
+     */
+    CONTACT_DATA,
+
+    /**
+     * Identifies the YANG config parsed data.
+     */
+    CONFIG_DATA,
+
+    /**
+     * Identifies the YANG description parsed data.
+     */
+    DESCRIPTION_DATA,
+
+    /**
+     * Identifies the YANG key parsed data.
+     */
+    KEY_DATA,
+
+    /**
+     * Identifies the YANG mandatory parsed data.
+     */
+    MANDATORY_DATA,
+
+    /**
+     * Identifies the YANG max element parsed data.
+     */
+    MAX_ELEMENT_DATA,
+
+    /**
+     * Identifies the YANG min element parsed data.
+     */
+    MIN_ELEMENT_DATA,
+
+    /**
+     * Identifies the YANG presence element parsed data.
+     */
+    PRESENCE_DATA,
+
+    /**
+     * Identifies the YANG reference element parsed data.
+     */
+    REFERENCE_DATA,
+
+    /**
+     * Identifies the YANG status element parsed data.
+     */
+    STATUS_DATA,
+
+    /**
+     * Identifies the YANG units element parsed data.
+     */
+    UNITS_DATA,
+
+    /**
+     * Identifies the YANG version element parsed data.
+     */
+    VERSION_DATA,
+
+    /**
+     * Identifies the YANG base element parsed data.
+     */
+    YANGBASE_DATA,
+
+    /**
+     * Identifies the YANG prefix element parsed data.
+     */
+    PREFIX_DATA,
+
+    /**
+     * Identifies the YANG default element parsed data.
+     */
+    DEFAULT_DATA,
+
+    /**
+     * Identifies the YANG organization parsed data.
+     */
+    ORGANIZATION_DATA;
+
+    /**
+     * Returns the YANG construct keyword corresponding to enum values.
+     *
+     * @param parsableDataType enum value for parsable data type.
+     * @return YANG construct keyword.
+     */
+    public static String getParsableDataType(ParsableDataType parsableDataType) {
+
+        switch (parsableDataType) {
+        case MODULE_DATA:
+            return "module";
+        case SUB_MODULE_DATA:
+            return "submodule";
+        case TYPEDEF_DATA:
+            return "typedef";
+        case TYPE_DATA:
+            return "type";
+        case CHOICE_DATA:
+            return "choice";
+        case CASE_DATA:
+            return "case";
+        case ENUMERATION_DATA:
+            return "enumeration";
+        case GROUPING_DATA:
+            return "grouping";
+        case USES_DATA:
+            return "uses";
+        case AUGMENT_DATA:
+            return "augment";
+        case CONTAINER_DATA:
+            return "container";
+        case LIST_DATA:
+            return "list";
+        case BELONGS_TO_DATA:
+            return "belongs-to";
+        case BIT_DATA:
+            return "bit";
+        case BITS_DATA:
+            return "bits";
+        case ENUM_DATA:
+            return "enum";
+        case IMPORT_DATA:
+            return "import";
+        case INCLUDE_DATA:
+            return "include";
+        case LEAF_DATA:
+            return "leaf";
+        case LEAF_LIST_DATA:
+            return "leaf-list";
+        case MUST_DATA:
+            return "must";
+        case REVISION_DATA:
+            return "revision";
+        case REVISION_DATE_DATA:
+            return "revision-date";
+        case NAMESPACE_DATA:
+            return "namespace";
+        case CONTACT_DATA:
+            return "contact";
+        case CONFIG_DATA:
+            return "config";
+        case DESCRIPTION_DATA:
+            return "description";
+        case KEY_DATA:
+            return "key";
+        case MANDATORY_DATA:
+            return "mandatory";
+        case MAX_ELEMENT_DATA:
+            return "max-elements";
+        case MIN_ELEMENT_DATA:
+            return "min-elements";
+        case PRESENCE_DATA:
+            return "presence";
+        case REFERENCE_DATA:
+            return "reference";
+        case STATUS_DATA:
+            return "status";
+        case UNITS_DATA:
+            return "units";
+        case VERSION_DATA:
+            return "version";
+        case YANGBASE_DATA:
+            return "yangbase";
+        case PREFIX_DATA:
+            return "prefix";
+        case ORGANIZATION_DATA:
+            return "organization";
+        case DEFAULT_DATA:
+            return "default";
+        default:
+            return "yang";
+        }
+    }
 }
\ No newline at end of file

@@ -19,13 +19,12 @@ package org.onosproject.yangutils.parser.exceptions;
 /**
  * Base class for exceptions in parser operations.
  */
-public class ParserException extends Exception {
+public class ParserException extends RuntimeException {
 
     private static final long serialVersionUID = 20160211L;
     private int lineNumber;
     private int charPositionInLine;
     private String fileName;
-    private String msg;
 
     /**
      * Create a new parser exception.
@@ -90,15 +89,6 @@ public class ParserException extends Exception {
     }
 
     /**
-     * Returns msg detail of exception in string.
-     *
-     * @return msg detail of exception in string
-     */
-    public String getMsg() {
-        return  this.msg;
-    }
-
-    /**
      * Sets line number of YANG file.
      *
      * @param line line number of YANG file
@@ -117,15 +107,6 @@ public class ParserException extends Exception {
     }
 
     /**
-     * Sets the detail of exception in string.
-     *
-     * @param msg the detail of exception in string
-     */
-    public void setMsg(String msg) {
-        this.msg = msg;
-    }
-
-    /**
      * Sets file name in parser exception.
      *
      * @param fileName YANG file name

@@ -69,16 +69,12 @@ public class YangUtilsParserManager implements YangUtilsParser {
         // Add customized error listener to catch errors during parsing.
         parser.addErrorListener(parseTreeErrorListener);
 
-        // Begin parsing YANG file and generate parse tree.
-        ParseTree tree = parser.yangfile();
+        ParseTree tree;
 
-        /**
-         * Throws an parser Exception if exception flag is set i.e. exception has
-         * occurred during parsing.
-         */
-        if (parseTreeErrorListener.isExceptionFlag()) {
-            // Get the exception occurred during parsing.
-            ParserException parserException = parseTreeErrorListener.getParserException();
+        try {
+            // Begin parsing YANG file and generate parse tree.
+            tree = parser.yangfile();
+        } catch (ParserException parserException) {
             parserException.setFileName(yangFile);
             throw parserException;
         }
@@ -93,15 +89,14 @@ public class YangUtilsParserManager implements YangUtilsParser {
           * Walk parse tree, provide call backs to methods in listener and
           * build data model tree.
           */
+        try {
             walker.walk(treeWalker, tree);
-
-        // Throws an parser exception which has occurred during listener walk.
-        if (treeWalker.getErrorInformation().isErrorFlag()) {
-            // Create object of listener exception
-            ParserException listenerException = new ParserException();
-            listenerException.setMsg(treeWalker.getErrorInformation().getErrorMsg());
+        } catch (ParserException listenerException) {
+            // TODO free incomplete data model tree.
             listenerException.setFileName(yangFile);
             throw listenerException;
+        } finally {
+            // TODO free parsable stack
         }
 
         // Returns the Root Node of the constructed data model tree.

@@ -16,8 +16,17 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -48,7 +57,11 @@ public final class BaseFileListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processYangFileEntry(TreeWalkListener listener, GeneratedYangParser.YangfileContext ctx) {
-        // TODO method implementation
+
+        // Check if stack is empty.
+        ListenerValidation.checkStackIsEmpty(listener, ListenerErrorType.INVALID_HOLDER,
+                                             ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.ENTRY);
+
     }
 
     /**
@@ -59,6 +72,25 @@ public final class BaseFileListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processYangFileExit(TreeWalkListener listener, GeneratedYangParser.YangfileContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.EXIT);
+
+        // Data Model tree root node is set.
+        if (listener.getParsedDataStack().peek() instanceof YangModule
+                | listener.getParsedDataStack().peek() instanceof YangSubModule) {
+            listener.setRootNode((YangNode) listener.getParsedDataStack().pop());
+        } else {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.INVALID_CHILD,
+                                                                             ParsableDataType.YANGBASE_DATA, "",
+                                                                             ListenerErrorLocation.EXIT));
+        }
+
+        // Check if stack is empty.
+        ListenerValidation.checkStackIsEmpty(listener, ListenerErrorType.INVALID_HOLDER,
+                                             ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.EXIT);
     }
 }
\ No newline at end of file

@@ -16,8 +16,17 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangBelongsTo;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -64,7 +73,18 @@ public final class BelongsToListener {
      */
     public static void processBelongsToEntry(TreeWalkListener listener,
                                              GeneratedYangParser.BelongstoStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.BELONGS_TO_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.ENTRY);
+
+        YangBelongsTo belongstoNode = new YangBelongsTo();
+        belongstoNode.setBelongsToModuleName(String.valueOf(ctx.IDENTIFIER().getText()));
+
+        // Push belongsto into the stack.
+        listener.getParsedDataStack().push(belongstoNode);
     }
 
     /**
@@ -76,6 +96,47 @@ public final class BelongsToListener {
      */
     public static void processBelongsToExit(TreeWalkListener listener,
                                             GeneratedYangParser.BelongstoStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.BELONGS_TO_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.EXIT);
+
+        Parsable tmpBelongstoNode = listener.getParsedDataStack().peek();
+        if (tmpBelongstoNode instanceof YangBelongsTo) {
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be empty.
+            ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                    ParsableDataType.BELONGS_TO_DATA,
+                                                    String.valueOf(ctx.IDENTIFIER().getText()),
+                                                    ListenerErrorLocation.EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getParsableDataType()) {
+            case SUB_MODULE_DATA: {
+                YangSubModule subModule = (YangSubModule) tmpNode;
+                subModule.setBelongsTo((YangBelongsTo) tmpBelongstoNode);
+                break;
+            }
+            default:
+                throw new ParserException(
+                                          ListenerErrorMessageConstruction
+                                                  .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                                 ParsableDataType.BELONGS_TO_DATA,
+                                                                                 String.valueOf(ctx.IDENTIFIER()
+                                                                                         .getText()),
+                                                                                 ListenerErrorLocation.EXIT));
+            }
+        } else {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
+                                                                             ParsableDataType.BELONGS_TO_DATA,
+                                                                             String.valueOf(ctx.IDENTIFIER()
+                                                                                     .getText()),
+                                                                             ListenerErrorLocation.EXIT));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,17 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -28,8 +37,7 @@ import org.onosproject.yangutils.parser.impl.TreeWalkListener;
  *                       [contact-stmt stmtsep]
  *                       [description-stmt stmtsep]
  *                       [reference-stmt stmtsep]
- * organization-stmt   = organization-keyword sep string
- *                            optsep stmtend
+ * contact-stmt        = contact-keyword sep string optsep stmtend
  *
  * ANTLR grammar rule
  * meta_stmts : organization_stmt? contact_stmt? description_stmt? reference_stmt?
@@ -57,7 +65,7 @@ import org.onosproject.yangutils.parser.impl.TreeWalkListener;
  *            | description_stmt? organization_stmt? contact_stmt? reference_stmt?
  *            | description_stmt? organization_stmt? reference_stmt? contact_stmt?
  *            ;
- * organization_stmt : ORGANIZATION_KEYWORD string STMTEND;
+ * contact_stmt : CONTACT_KEYWORD string STMTEND;
  */
 
 /**
@@ -81,6 +89,32 @@ public final class ContactListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processContactEntry(TreeWalkListener listener, GeneratedYangParser.ContactStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.CONTACT_DATA,
+                                                String.valueOf(ctx.string().getText()), ListenerErrorLocation.ENTRY);
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+        case MODULE_DATA: {
+            YangModule module = (YangModule) tmpNode;
+            module.setContact(String.valueOf(ctx.string().getText()));
+            break;
+        }
+        case SUB_MODULE_DATA: {
+            YangSubModule subModule = (YangSubModule) tmpNode;
+            subModule.setContact(String.valueOf(ctx.string().getText()));
+            break;
+        }
+        default:
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                             ParsableDataType.CONTACT_DATA,
+                                                                             String.valueOf(ctx.string().getText()),
+                                                                             ListenerErrorLocation.ENTRY));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,18 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangImport;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -62,7 +72,18 @@ public final class ImportListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processImportEntry(TreeWalkListener listener, GeneratedYangParser.ImportStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.IMPORT_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.ENTRY);
+
+        YangImport importNode = new YangImport();
+        importNode.setModuleName(String.valueOf(ctx.IDENTIFIER().getText()));
+
+        // Push import node to the stack.
+        listener.getParsedDataStack().push(importNode);
     }
 
     /**
@@ -73,6 +94,52 @@ public final class ImportListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processImportExit(TreeWalkListener listener, GeneratedYangParser.ImportStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.IMPORT_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.EXIT);
+
+        Parsable tmpImportNode = listener.getParsedDataStack().peek();
+        if (tmpImportNode instanceof YangImport) {
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                    ParsableDataType.IMPORT_DATA,
+                                                    String.valueOf(ctx.IDENTIFIER().getText()),
+                                                    ListenerErrorLocation.EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getParsableDataType()) {
+            case MODULE_DATA: {
+                YangModule module = (YangModule) tmpNode;
+                module.addImportedInfo((YangImport) tmpImportNode);
+                break;
+            }
+            case SUB_MODULE_DATA: {
+                YangSubModule subModule = (YangSubModule) tmpNode;
+                subModule.addImportedInfo((YangImport) tmpImportNode);
+                break;
+            }
+            default:
+                throw new ParserException(
+                                          ListenerErrorMessageConstruction
+                                                  .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                                 ParsableDataType.IMPORT_DATA,
+                                                                                 String.valueOf(ctx.IDENTIFIER()
+                                                                                         .getText()),
+                                                                                 ListenerErrorLocation.EXIT));
+            }
+        } else {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
+                                                                             ParsableDataType.IMPORT_DATA, String
+                                                                                     .valueOf(ctx.IDENTIFIER()
+                                                                                             .getText()),
+                                                                             ListenerErrorLocation.EXIT));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,18 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangInclude;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -37,7 +47,7 @@ import org.onosproject.yangutils.parser.impl.TreeWalkListener;
  * linkage_stmts : (import_stmt
  *               | include_stmt)*;
  * include_stmt : INCLUDE_KEYWORD IDENTIFIER (STMTEND | LEFT_CURLY_BRACE
- *                revision_date_stmt_body? RIGHT_CURLY_BRACE);
+ *                revision_date_stmt? RIGHT_CURLY_BRACE);
  */
 
 /**
@@ -61,7 +71,17 @@ public final class IncludeListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processIncludeEntry(TreeWalkListener listener, GeneratedYangParser.IncludeStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.INCLUDE_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.ENTRY);
+
+        YangInclude includeNode = new YangInclude();
+        includeNode.setSubModuleName(String.valueOf(ctx.IDENTIFIER().getText()));
+
+        listener.getParsedDataStack().push(includeNode);
     }
 
     /**
@@ -72,6 +92,52 @@ public final class IncludeListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processIncludeExit(TreeWalkListener listener, GeneratedYangParser.IncludeStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.INCLUDE_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.EXIT);
+
+        Parsable tmpIncludeNode = listener.getParsedDataStack().peek();
+        if (tmpIncludeNode instanceof YangInclude) {
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                    ParsableDataType.INCLUDE_DATA,
+                                                    String.valueOf(ctx.IDENTIFIER().getText()),
+                                                    ListenerErrorLocation.EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getParsableDataType()) {
+            case MODULE_DATA: {
+                YangModule module = (YangModule) tmpNode;
+                module.addIncludedInfo((YangInclude) tmpIncludeNode);
+                break;
+            }
+            case SUB_MODULE_DATA: {
+                YangSubModule subModule = (YangSubModule) tmpNode;
+                subModule.addIncludedInfo((YangInclude) tmpIncludeNode);
+                break;
+            }
+            default:
+                throw new ParserException(
+                                          ListenerErrorMessageConstruction
+                                                  .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                                 ParsableDataType.INCLUDE_DATA,
+                                                                                 String.valueOf(ctx.IDENTIFIER()
+                                                                                         .getText()),
+                                                                                 ListenerErrorLocation.EXIT));
+            }
+        } else {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
+                                                                             ParsableDataType.INCLUDE_DATA, String
+                                                                                     .valueOf(ctx.IDENTIFIER()
+                                                                                             .getText()),
+                                                                             ListenerErrorLocation.EXIT));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,15 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -58,7 +65,16 @@ public final class ModuleListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processModuleEntry(TreeWalkListener listener, GeneratedYangParser.ModuleStatementContext ctx) {
-        // TODO method implementation
+
+        // Check if stack is empty.
+        ListenerValidation
+                .checkStackIsEmpty(listener, ListenerErrorType.INVALID_HOLDER, ParsableDataType.MODULE_DATA,
+                                   String.valueOf(ctx.IDENTIFIER().getText()), ListenerErrorLocation.ENTRY);
+
+        YangModule yangModule = new YangModule();
+        yangModule.setName(ctx.IDENTIFIER().getText());
+
+        listener.getParsedDataStack().push(yangModule);
     }
 
     /**
@@ -69,6 +85,21 @@ public final class ModuleListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processModuleExit(TreeWalkListener listener, GeneratedYangParser.ModuleStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.MODULE_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.EXIT);
+
+        if (!(listener.getParsedDataStack().peek() instanceof YangModule)) {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
+                                                                             ParsableDataType.MODULE_DATA, String
+                                                                                     .valueOf(ctx.IDENTIFIER()
+                                                                                             .getText()),
+                                                                             ListenerErrorLocation.EXIT));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,19 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNameSpace;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import java.net.URI;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -63,6 +74,53 @@ public final class NamespaceListener {
      */
     public static void processNamespaceEntry(TreeWalkListener listener,
                                              GeneratedYangParser.NamespaceStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.NAMESPACE_DATA,
+                                                String.valueOf(ctx.string().getText()), ListenerErrorLocation.ENTRY);
+
+        if (!validateUriValue(String.valueOf(ctx.string().getText()))) {
+            ParserException parserException = new ParserException("Invalid namespace URI");
+            parserException.setLine(ctx.string().STRING(0).getSymbol().getLine());
+            parserException.setCharPosition(ctx.string().STRING(0).getSymbol().getCharPositionInLine());
+            throw parserException;
+        }
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+        case MODULE_DATA: {
+            YangModule module = (YangModule) tmpNode;
+            YangNameSpace uri = new YangNameSpace();
+            uri.setUri(String.valueOf(ctx.string().getText()));
+            module.setNameSpace(uri);
+            break;
+        }
+        default:
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                             ParsableDataType.NAMESPACE_DATA,
+                                                                             String.valueOf(ctx.string().getText()),
+                                                                             ListenerErrorLocation.ENTRY));
+        }
+    }
+
+    /**
+     * Validate input URI.
+     *
+     * @param uri input namespace URI
+     * @return validation result
+     */
+    private static boolean validateUriValue(String uri) {
+        uri = uri.replace("\"", "");
+        final URI tmpUri;
+        try {
+            tmpUri = URI.create(uri);
+        } catch (Exception e1) {
+            return false;
+        }
+        return true;
     }
 }
\ No newline at end of file

@@ -16,8 +16,17 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -28,7 +37,8 @@ import org.onosproject.yangutils.parser.impl.TreeWalkListener;
  *                       [contact-stmt stmtsep]
  *                       [description-stmt stmtsep]
  *                       [reference-stmt stmtsep]
- * contact-stmt        = contact-keyword sep string optsep stmtend
+ * organization-stmt   = organization-keyword sep string
+ *                            optsep stmtend
  *
  * ANTLR grammar rule
  * meta_stmts : organization_stmt? contact_stmt? description_stmt? reference_stmt?
@@ -56,7 +66,7 @@ import org.onosproject.yangutils.parser.impl.TreeWalkListener;
  *            | description_stmt? organization_stmt? contact_stmt? reference_stmt?
  *            | description_stmt? organization_stmt? reference_stmt? contact_stmt?
  *            ;
- * contact_stmt : CONTACT_KEYWORD string STMTEND;
+ * organization_stmt : ORGANIZATION_KEYWORD string STMTEND;
  */
 
 /**
@@ -81,6 +91,32 @@ public final class OrganizationListener {
      */
     public static void processOrganizationEntry(TreeWalkListener listener,
                                                 GeneratedYangParser.OrganizationStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.ORGANIZATION_DATA,
+                                                String.valueOf(ctx.string().getText()), ListenerErrorLocation.ENTRY);
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+        case MODULE_DATA: {
+            YangModule module = (YangModule) tmpNode;
+            module.setOrganization(String.valueOf(ctx.string().getText()));
+            break;
+        }
+        case SUB_MODULE_DATA: {
+            YangSubModule subModule = (YangSubModule) tmpNode;
+            subModule.setOrganization(String.valueOf(ctx.string().getText()));
+            break;
+        }
+        default:
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                             ParsableDataType.ORGANIZATION_DATA,
+                                                                             String.valueOf(ctx.string().getText()),
+                                                                             ListenerErrorLocation.ENTRY));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,18 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangBelongsTo;
+import org.onosproject.yangutils.datamodel.YangImport;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -63,6 +73,39 @@ public final class PrefixListener {
      * @param ctx context object of the grammar rule.
      */
     public static void processPrefixEntry(TreeWalkListener listener, GeneratedYangParser.PrefixStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.PREFIX_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.ENTRY);
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+        case MODULE_DATA: {
+            YangModule module = (YangModule) tmpNode;
+            module.setPrefix(ctx.IDENTIFIER().getText());
+            break;
+        }
+        case IMPORT_DATA: {
+            YangImport importNode = (YangImport) tmpNode;
+            importNode.setPrefixId(ctx.IDENTIFIER().getText());
+            break;
+        }
+        case BELONGS_TO_DATA: {
+            YangBelongsTo belongstoNode = (YangBelongsTo) tmpNode;
+            belongstoNode.setPrefix(ctx.IDENTIFIER().getText());
+            break;
+        }
+        default:
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                             ParsableDataType.PREFIX_DATA, String
+                                                                                     .valueOf(ctx.IDENTIFIER()
+                                                                                             .getText()),
+                                                                             ListenerErrorLocation.ENTRY));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,17 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangImport;
+import org.onosproject.yangutils.datamodel.YangInclude;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -69,6 +78,34 @@ public final class RevisionDateListener {
      */
     public static void processRevisionDateEntry(TreeWalkListener listener,
                                                 GeneratedYangParser.RevisionDateStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.REVISION_DATE_DATA,
+                                                String.valueOf(ctx.DATE_ARG().getText()),
+                                                ListenerErrorLocation.ENTRY);
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+        case IMPORT_DATA: {
+            YangImport importNode = (YangImport) tmpNode;
+            importNode.setRevision(String.valueOf(ctx.DATE_ARG().getText()));
+            break;
+        }
+        case INCLUDE_DATA: {
+            YangInclude includeNode = (YangInclude) tmpNode;
+            includeNode.setRevision(String.valueOf(ctx.DATE_ARG().getText()));
+            break;
+        }
+        default:
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                             ParsableDataType.REVISION_DATE_DATA,
+                                                                             String.valueOf(ctx.DATE_ARG().getText()),
+                                                                             ListenerErrorLocation.ENTRY));
+        }
     }
+    // TODO Implement the DATE_ARG validation as per RFC 6020.
 }
\ No newline at end of file

@@ -16,8 +16,18 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangRevision;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -59,28 +69,94 @@ public final class RevisionListener {
     private RevisionListener() {
     }
 
+    public static void processRevisionEntry(TreeWalkListener listener,
+                                            GeneratedYangParser.RevisionStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.REVISION_DATA,
+                                                String.valueOf(ctx.DATE_ARG().getText()),
+                                                ListenerErrorLocation.ENTRY);
+
+        // Validate for reverse chronological order of revision & for revision value.
+        if (!validateRevision(listener, ctx)) {
+            return;
+            // TODO to be implemented.
+        }
+
+        YangRevision revisionNode = new YangRevision();
+        revisionNode.setRevDate(String.valueOf(ctx.DATE_ARG().getText()));
+
+        listener.getParsedDataStack().push(revisionNode);
+    }
+
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (revision), perform validations and update the data model
-     * tree.
+     * It is called when parser exits from grammar rule (revision), it perform
+     * validations and update the data model tree.
      *
      * @param listener Listener's object.
      * @param ctx context object of the grammar rule.
      */
-    public static void processRevisionEntry(TreeWalkListener listener, GeneratedYangParser.RevisionStatementContext
-            ctx) {
-        // TODO method implementation
+    public static void processRevisionExit(TreeWalkListener listener,
+                                           GeneratedYangParser.RevisionStatementContext ctx) {
+
+        // Check for stack to be non empty.
+        ListenerValidation
+                .checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER, ParsableDataType.REVISION_DATA,
+                                      String.valueOf(ctx.DATE_ARG().getText()), ListenerErrorLocation.EXIT);
+
+        Parsable tmpRevisionNode = listener.getParsedDataStack().peek();
+        if (tmpRevisionNode instanceof YangRevision) {
+            listener.getParsedDataStack().pop();
+
+            // Check for stack to be non empty.
+            ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                    ParsableDataType.REVISION_DATA,
+                                                    String.valueOf(ctx.DATE_ARG().getText()),
+                                                    ListenerErrorLocation.EXIT);
+
+            Parsable tmpNode = listener.getParsedDataStack().peek();
+            switch (tmpNode.getParsableDataType()) {
+            case MODULE_DATA: {
+                YangModule module = (YangModule) tmpNode;
+                module.setRevision((YangRevision) tmpRevisionNode);
+                break;
+            }
+            case SUB_MODULE_DATA: {
+                YangSubModule subModule = (YangSubModule) tmpNode;
+                subModule.setRevision((YangRevision) tmpRevisionNode);
+                break;
+            }
+            default:
+                throw new ParserException(
+                                          ListenerErrorMessageConstruction
+                                                  .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                                                 ParsableDataType.REVISION_DATA,
+                                                                                 String.valueOf(ctx.DATE_ARG()
+                                                                                         .getText()),
+                                                                                 ListenerErrorLocation.EXIT));
+            }
+        } else {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
+                                                                             ParsableDataType.REVISION_DATA, String
+                                                                                     .valueOf(ctx.DATE_ARG()
+                                                                                             .getText()),
+                                                                             ListenerErrorLocation.EXIT));
+        }
     }
 
     /**
-     * It is called when parser exits from grammar rule (revision), it perform
-     * validations and update the data model tree.
+     * Validate revision.
      *
      * @param listener Listener's object.
      * @param ctx context object of the grammar rule.
+     * @return validation result
      */
-    public static void processRevisionExit(TreeWalkListener listener, GeneratedYangParser.RevisionStatementContext
-            ctx) {
-        // TODO method implementation
+    private static boolean validateRevision(TreeWalkListener listener,
+                                            GeneratedYangParser.RevisionStatementContext ctx) {
+        // TODO to be implemented
+        return true;
     }
 }
\ No newline at end of file

@@ -16,8 +16,15 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -60,7 +67,16 @@ public final class SubModuleListener {
      */
     public static void processSubModuleEntry(TreeWalkListener listener,
                                              GeneratedYangParser.SubModuleStatementContext ctx) {
-        // TODO method implementation
+
+        // Check if stack is empty.
+        ListenerValidation
+                .checkStackIsEmpty(listener, ListenerErrorType.INVALID_HOLDER, ParsableDataType.SUB_MODULE_DATA,
+                                   String.valueOf(ctx.IDENTIFIER().getText()), ListenerErrorLocation.ENTRY);
+
+        YangSubModule yangSubModule = new YangSubModule();
+        yangSubModule.setName(ctx.IDENTIFIER().getText());
+
+        listener.getParsedDataStack().push(yangSubModule);
     }
 
     /**
@@ -72,6 +88,21 @@ public final class SubModuleListener {
      */
     public static void processSubModuleExit(TreeWalkListener listener,
                                             GeneratedYangParser.SubModuleStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.SUB_MODULE_DATA,
+                                                String.valueOf(ctx.IDENTIFIER().getText()),
+                                                ListenerErrorLocation.EXIT);
+
+        if (!(listener.getParsedDataStack().peek() instanceof YangSubModule)) {
+            throw new ParserException(
+                                      ListenerErrorMessageConstruction
+                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
+                                                                             ParsableDataType.SUB_MODULE_DATA,
+                                                                             String.valueOf(ctx.IDENTIFIER()
+                                                                                     .getText()),
+                                                                             ListenerErrorLocation.EXIT));
+        }
     }
 }
\ No newline at end of file

@@ -16,8 +16,17 @@
 
 package org.onosproject.yangutils.parser.impl.listeners;
 
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.Parsable;
+import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -73,6 +82,48 @@ public final class VersionListener {
      */
     public static void processVersionEntry(TreeWalkListener listener,
                                            GeneratedYangParser.YangVersionStatementContext ctx) {
-        // TODO method implementation
+
+        // Check for stack to be non empty.
+        ListenerValidation
+                .checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER, ParsableDataType.VERSION_DATA,
+                                      String.valueOf(ctx.INTEGER().getText()), ListenerErrorLocation.ENTRY);
+
+        Integer version = Integer.valueOf(ctx.INTEGER().getText());
+        if (!isVersionValid(version)) {
+            ParserException parserException = new ParserException("Input version not supported");
+            parserException.setLine(ctx.INTEGER().getSymbol().getLine());
+            parserException.setCharPosition(ctx.INTEGER().getSymbol().getCharPositionInLine());
+            throw parserException;
+        }
+
+        // Obtain the node of the stack.
+        Parsable tmpNode = listener.getParsedDataStack().peek();
+        switch (tmpNode.getParsableDataType()) {
+        case MODULE_DATA: {
+            YangModule module = (YangModule) tmpNode;
+            module.setVersion((byte) 1);
+            break;
+        }
+        case SUB_MODULE_DATA: {
+            YangSubModule subModule = (YangSubModule) tmpNode;
+            subModule.setVersion((byte) 1);
+            break;
+        }
+        default:
+            throw new ParserException(ListenerErrorMessageConstruction.
+                    constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                            ParsableDataType.VERSION_DATA, String.valueOf(ctx.INTEGER().getText()),
+                            ListenerErrorLocation.ENTRY));
+        }
+    }
+
+    /**
+     * Validates whether the value of YANG version.
+     *
+     * @param version input yang version
+     * @return validation result
+     */
+    private static boolean isVersionValid(Integer version) {
+        return version == 1;
     }
 }
\ No newline at end of file

@@ -21,12 +21,18 @@ package org.onosproject.yangutils.parser.impl.parserutils;
  */
 public class ListenerError {
 
-    // Maintains the state of Exception.
+    // Maintains the state of exception.
     private boolean errorFlag = false;
 
-    // Maintains the reason of Exception.
+    // Maintains the reason of exception.
     private String errorMsg;
 
+    // Maintains the line number of exception.
+    private int lineNumber;
+
+    // Maintains the character position in lin of exception.
+    private int charPositionInLine;
+
     /**
      * Returns error flag.
      *
@@ -37,18 +43,36 @@ public class ListenerError {
     }
 
     /**
-     * Returns error message.
+     * Returns reason for error.
      *
-     * @return error msg.
+     * @return error message
      */
     public String getErrorMsg() {
         return errorMsg;
     }
 
     /**
+     * Returns error line number.
+     *
+     * @return error line number.
+     */
+    public int getLineNumber() {
+        return lineNumber;
+    }
+
+    /**
+     * Returns error position in line.
+     *
+     * @return error character position in line.
+     */
+    public int getCharPositionInLine() {
+        return charPositionInLine;
+    }
+
+    /**
      * Set error flag.
      *
-     * @param errorFlag error existence flag
+     * @param errorFlag error existence flag.
      */
     public void setErrorFlag(boolean errorFlag) {
         this.errorFlag = errorFlag;
@@ -62,4 +86,22 @@ public class ListenerError {
     public void setErrorMsg(String errorMsg) {
         this.errorMsg = errorMsg;
     }
+
+    /**
+     * Set error line number.
+     *
+     * @param lineNumber line number of error.
+     */
+    public void setLineNumber(int lineNumber) {
+        this.lineNumber = lineNumber;
+    }
+
+    /**
+     * Set error character position in line.
+     *
+     * @param charPositionInLine error character position in line.
+     */
+    public void setCharPositionInLine(int charPositionInLine) {
+        this.charPositionInLine = charPositionInLine;
+    }
 }
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.parserutils;
+
+/**
+ * Maintains listener error location.
+ */
+public enum ListenerErrorLocation {
+    /**
+     * Represents that the error location is before processing.
+     */
+    ENTRY(),
+
+    /**
+     * Represents that the error location is before processing.
+     */
+    EXIT();
+
+    /**
+     * Returns the message corresponding to listener error location.
+     *
+     * @param errorLocation enum value for type of error.
+     * @return message corresponding to listener error location.
+     */
+    public static String getErrorLocationMessage(ListenerErrorLocation errorLocation) {
+
+        switch (errorLocation) {
+        case ENTRY:
+            return "before";
+        case EXIT:
+            return "after";
+        default:
+            return "during";
+        }
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.parserutils;
+
+import org.onosproject.yangutils.parser.ParsableDataType;
+
+/**
+ * It's a utility to help construct detailed error message.
+ */
+public final class ListenerErrorMessageConstruction {
+
+    /**
+     * Private constructor.
+     */
+    private ListenerErrorMessageConstruction() {
+    }
+
+    /**
+     * Constructs message for error with extended information and returns the same.
+     *
+     * @param errorType            error type needs to be set in error message.
+     * @param parsableDataType     type of parsable data in which error occurred.
+     * @param parsableDataTypeName identifier/string of parsable data type in which error occurred.
+     * @param errorLocation        location where error occurred.
+     * @param extendedErrorInformation  extended error information.
+     * @return constructed error message.
+     */
+    public static String constructExtendedListenerErrorMessage(ListenerErrorType errorType,
+                                                               ParsableDataType parsableDataType,
+                                                               String parsableDataTypeName,
+                                                               ListenerErrorLocation errorLocation,
+                                                               String extendedErrorInformation) {
+        String newErrorMessage;
+        newErrorMessage = constructListenerErrorMessage(errorType, parsableDataType, parsableDataTypeName,
+                errorLocation) + "\n" + "Error Information: " + extendedErrorInformation;
+        return newErrorMessage;
+    }
+
+    /**
+     * Constructs message for error during listener based tree walk and returns the same.
+     *
+     * @param errorType error type needs to be set in error message.
+     * @param parsableDataType type of parsable data in which error occurred.
+     * @param parsableDataTypeName identifier/string of parsable data type in which error occurred.
+     * @param errorLocation location where error occurred.
+     * @return constructed error message.
+     */
+    public static String constructListenerErrorMessage(ListenerErrorType errorType,
+                                                       ParsableDataType parsableDataType,
+                                                       String parsableDataTypeName,
+                                                       ListenerErrorLocation errorLocation) {
+
+        String errorMessage;
+
+        errorMessage = "Internal parser error detected: " + ListenerErrorType.getErrorType(errorType) + " "
+                + ParsableDataType.getParsableDataType(parsableDataType);
+
+
+        if (!parsableDataTypeName.isEmpty()) {
+            errorMessage = errorMessage + " \"" + parsableDataTypeName + "\" ";
+        } else {
+            errorMessage = errorMessage + " ";
+
+        }
+        errorMessage = errorMessage + ListenerErrorLocation.getErrorLocationMessage(errorLocation) + " processing.";
+        return errorMessage;
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.parserutils;
+
+/**
+ * Maintains listener error type.
+ */
+public enum ListenerErrorType {
+    /**
+     * Represents the parent holder in parsable stack for given YANG construct is invalid.
+     */
+    INVALID_HOLDER(),
+
+    /**
+     * Represents the parent holder in parsable stack for given YANG construct is missing.
+     */
+    MISSING_HOLDER(),
+
+    /**
+     * Represents the current holder in parsable stack for given YANG construct is missing.
+     */
+    MISSING_CURRENT_HOLDER(),
+
+    /**
+     * Represents that the child in parsable stack for given YANG construct is invalid.
+     */
+    INVALID_CHILD(),
+
+    /**
+     * Represents that the cardinality for given YANG construct is invalid.
+     */
+    INVALID_CARDINALITY(),
+
+    /**
+     * Represents that some of earlier parsed data is not handled correctly.
+     */
+    UNHANDLED_PARSED_DATA();
+
+    /**
+     * Returns the message corresponding to listener error type.
+     *
+     * @param errorType enum value for type of error.
+     * @return message corresponding to listener error type.
+     */
+    public static String getErrorType(ListenerErrorType errorType) {
+
+        switch (errorType) {
+        case INVALID_HOLDER:
+            return "Invalid holder for";
+        case MISSING_HOLDER:
+            return "Missing holder at";
+        case MISSING_CURRENT_HOLDER:
+            return "Missing";
+        case INVALID_CHILD:
+            return "Invalid child in";
+        case INVALID_CARDINALITY:
+            return "Invalid cardinality in";
+        case UNHANDLED_PARSED_DATA:
+            return "Unhandled parsed data at";
+        default:
+            return "Problem in";
+        }
+    }
+}
\ No newline at end of file

@@ -16,39 +16,66 @@
 
 package org.onosproject.yangutils.parser.impl.parserutils;
 
+import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
 
 /**
- * Its a utility to carry out listener validation.
+ * It's a utility to carry out listener validation.
  */
 public final class ListenerValidation {
 
     /**
-     * Creates a new belongto listener.
+     * Creates a new listener validation.
      */
     private ListenerValidation() {
     }
 
     /**
-     * Checks if error is set or parsed data stack is empty.
+     * Checks parsed data stack is not empty.
      *
      * @param listener Listener's object.
-     * @param errNode parsable node for which validation needs to be done.
-     * @return validation result.
+     * @param errorType error type needs to be set in error message.
+     * @param parsableDataType type of parsable data in which error occurred.
+     * @param parsableDataTypeName name of parsable data type in which error occurred.
+     * @param errorLocation location where error occurred.
      */
-    public static boolean preValidation(TreeWalkListener listener, String errNode) {
-
-        // Check whether error found while walking YANG file, if yes return true.
-        if (listener.getErrorInformation().isErrorFlag()) {
-            return true;
+    public static void checkStackIsNotEmpty(TreeWalkListener listener, ListenerErrorType errorType,
+                                               ParsableDataType parsableDataType, String parsableDataTypeName,
+                                               ListenerErrorLocation errorLocation) {
+        if (listener.getParsedDataStack().empty()) {
+            /*
+             * If stack is empty it indicates error condition, value of parsableDataTypeName will be null in case there
+             * is no name attached to parsable data type.
+             */
+            String message = ListenerErrorMessageConstruction.constructListenerErrorMessage(errorType, parsableDataType,
+                    parsableDataTypeName, errorLocation);
+            throw new ParserException(message);
+        }
     }
 
-        // If stack is empty it indicates error condition
-        if (listener.getParsedDataStack().empty()) {
-            listener.getErrorInformation().setErrorFlag(true);
-            listener.getErrorInformation().setErrorMsg("Parsable stack empty at" + errNode + "entry");
-            return true;
+    /**
+     * Checks parsed data stack is empty.
+     *
+     * @param listener Listener's object.
+     * @param errorType error type needs to be set in error message.
+     * @param parsableDataType type of parsable data in which error occurred.
+     * @param parsableDataTypeName name of parsable data type in which error occurred.
+     * @param errorLocation location where error occurred.
+     */
+
+    public static void checkStackIsEmpty(TreeWalkListener listener, ListenerErrorType errorType,
+                                            ParsableDataType parsableDataType, String parsableDataTypeName,
+                                            ListenerErrorLocation errorLocation) {
+
+        if (!listener.getParsedDataStack().empty()) {
+            /*
+             * If stack is empty it indicates error condition, value of parsableDataTypeName will be null in case there
+             * is no name attached to parsable data type.
+             */
+            String message = ListenerErrorMessageConstruction.constructListenerErrorMessage(errorType, parsableDataType,
+                    parsableDataTypeName, errorLocation);
+            throw new ParserException(message);
         }
-        return false;
     }
 }
\ No newline at end of file

@@ -29,37 +29,13 @@ import org.onosproject.yangutils.parser.exceptions.ParserException;
  */
 public class ParseTreeErrorListener extends BaseErrorListener {
 
-    // Exception of type parser exceptions are catched during parsing.
-    private ParserException parserException = new ParserException();
-
-    // Flag to indicate presence of exception.
-    private boolean exceptionFlag = false;
-
-    /**
-     * Returns the status of exception flag.
-     *
-     * @return flag which contains the status of exception.
-     */
-    public boolean isExceptionFlag() {
-        return exceptionFlag;
-    }
-
-    /**
-     * Returns the parser exception object populated with line, character
-     * position and message.
-     *
-     * @return object of parser exception.
-     */
-    public ParserException getParserException() {
-        return parserException;
-    }
-
     @Override
     public void syntaxError(Recognizer<?, ?> recognizer, Object offendingSymbol, int line, int charPositionInLine,
                             String msg, RecognitionException e) {
+
+        ParserException parserException = new ParserException(msg);
         parserException.setLine(line);
         parserException.setCharPosition(charPositionInLine);
-        parserException.setMsg(msg);
-        exceptionFlag = true;
+        throw parserException;
     }
 }
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl;
+
+import org.hamcrest.Description;
+import org.hamcrest.TypeSafeMatcher;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+
+/**
+ * ExpectedException framework can use the Hamcrest matcher's to test
+ * custom/extended exceptions. This class extends the type safe matcher to define
+ * the custom exception matcher.
+ */
+public final class CustomExceptionMatcher extends TypeSafeMatcher<ParserException> {
+
+    /**
+     * Customized exception matcher to match error location.
+     *
+     * @param line error line
+     * @param charPosition error character position
+     * @return
+     */
+    public static CustomExceptionMatcher errorLocation(int line, int charPosition) {
+        return new CustomExceptionMatcher(line, charPosition);
+    }
+
+    private int actualLine;
+    private final int expectedLine;
+    private int actualCharPosition;
+    private final int expectedCharPosition;
+
+    private CustomExceptionMatcher(int expectedLine, int expectedCharPosition) {
+        this.expectedLine = expectedLine;
+        this.expectedCharPosition = expectedCharPosition;
+    }
+
+    @Override
+    protected boolean matchesSafely(final ParserException exception) {
+        actualLine = exception.getLineNumber();
+        actualCharPosition = exception.getCharPositionInLine();
+        return ((actualLine == expectedLine) && (actualCharPosition == expectedCharPosition));
+    }
+
+    @Override
+    public void describeTo(Description description) {
+        description.appendText(" Error reported location ")
+                .appendText("Line " + actualLine + ", " + "CharPosition " + actualCharPosition)
+                .appendText(" instead of expected ")
+                .appendText("Line " + expectedLine + ", " + "CharPosition " + expectedCharPosition);
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.TreeWalkListener;
+
+/**
+ * Test cases for testing base rule listener functionality.
+ */
+public class BaseFileListenerTest {
+
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    /**
+     * Checks for exception if stack of parsable data is not empty at the entry
+     * of yang base rule.
+     */
+    @Test
+    public void processYangFileEntryNonEmptyStack() {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("Internal parser error detected: Invalid holder for yangbase before processing.");
+
+        YangModule tmpModule = new YangModule();
+        TreeWalkListener listener = new TreeWalkListener();
+        listener.getParsedDataStack().push(tmpModule);
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileEntry(listener, ctx);
+    }
+
+    /**
+     * Checks that exception shouldn't be generated if stack of parsable data is
+     * empty at the entry of yang base rule.
+     */
+    @Test
+    public void processYangFileEntryEmptyStack() {
+
+        TreeWalkListener listener = new TreeWalkListener();
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileEntry(listener, ctx);
+    }
+
+    /**
+     * Checks that exception should be generated if stack of parsable data is
+     * not empty at the exit of yang base rule.
+     */
+    @Test
+    public void processYangFileExitEmptyStack() {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("Internal parser error detected: Missing holder at yangbase after processing.");
+
+        TreeWalkListener listener = new TreeWalkListener();
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileExit(listener, ctx);
+    }
+
+    /**
+     * Checks that exception shouldn't be generated if stack of parsable data is
+     * empty at the exit of yang base rule.
+     */
+    @Test
+    public void processYangFileExitNonEmptyStack() {
+
+        TreeWalkListener listener = new TreeWalkListener();
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileEntry(listener, ctx);
+    }
+
+    /**
+     * Checks that after popping out the parsable node from stack it should be
+     * empty.
+     */
+    @Test
+    public void processYangFileExitStackErrorExtraEntryTest() {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("Internal parser error detected: Invalid holder for yangbase after processing.");
+
+        YangModule tmpModule = new YangModule();
+        YangModule tmpModule2 = new YangModule();
+        TreeWalkListener listener = new TreeWalkListener();
+        listener.getParsedDataStack().push(tmpModule);
+        listener.getParsedDataStack().push(tmpModule2);
+        GeneratedYangParser.YangfileContext ctx = null;
+        BaseFileListener.processYangFileExit(listener, ctx);
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.CustomExceptionMatcher;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing belongsto listener functionality.
+ */
+public class BelongstoListenerTest {
+
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if mandatory belongsto parameter "prefix" is not present.
+     */
+    @Test
+    public void processBelongsToWithoutPrefix() throws IOException, ParserException {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("mismatched input '}' expecting 'prefix'");
+        thrown.expect(CustomExceptionMatcher.errorLocation(4, 0));
+        YangNode node = manager.getDataModel("src/test/resources/BelongsToWithoutPrefix.yang");
+    }
+
+    /**
+     * Checks that prefix must be present only once in belongsto.
+     */
+    @Test
+    public void processBelongsToDualPrefix() throws IOException, ParserException {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("mismatched input 'prefix' expecting '}'");
+        thrown.expect(CustomExceptionMatcher.errorLocation(5, 0));
+        YangNode node = manager.getDataModel("src/test/resources/BelongsToDualPrefix.yang");
+    }
+
+    /**
+     * Checks if belongsto listener updates the date model tree.
+     */
+    @Test
+    public void processBelongsToWithPrefix() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/BelongsToWithPrefix.yang");
+        YangSubModule yangNode = (YangSubModule) node;
+        assertThat(yangNode.getBelongsTo().getBelongsToModuleName(), is("ONOS"));
+    }
+
+    /**
+     * Checks if mandatory parameter "belongsto" is present.
+     */
+    @Test
+    public void processSubModuleWithoutBelongsTo() throws IOException, ParserException {
+        thrown.expect(ParserException.class);
+        thrown.expectMessage("mismatched input '}' expecting 'belongs-to'");
+        thrown.expect(CustomExceptionMatcher.errorLocation(3, 0));
+        YangNode node = manager.getDataModel("src/test/resources/SubModuleWithoutBelongsTo.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing contact listener functionality.
+ */
+public class ContactListenerTest {
+
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if contact listener updates the data model tree.
+     */
+    @Test
+    public void processContactValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ContactValidEntry.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getContact(), is("\"WG List:  <mailto:spring@ietf.org>\nEditor:    "
+                + "Stephane Litkowski\n           " + "<mailto:stephane.litkowski@orange.com>\""));
+    }
+
+    /**
+     * Checks that contact must be present only once.
+     */
+    @Test(expected = ParserException.class)
+    public void processContactDualEntryTest() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ContactDualEntryTest.yang");
+
+    }
+
+    /**
+     * Checks if contact is not empty.
+     */
+    @Test(expected = ParserException.class)
+    public void processContactWithEmptyString() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ContactWithEmptyString.yang");
+    }
+
+    /**
+     * Checks that contact must be present after namespace.
+     */
+    @Test(expected = ParserException.class)
+    public void processContactIncorrectOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ContactIncorrectOrder.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing import listener functionality.
+ */
+public class ImportListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if mandatory parameter prefix is present in import.
+     */
+    @Test(expected = ParserException.class)
+    public void processImportWithoutPrefix() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ImportWithoutPrefix.yang");
+    }
+
+    /**
+     * Checks that prefix must be present only once in import.
+     */
+    @Test(expected = ParserException.class)
+    public void processImportWithDualPrefix() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ImportWithDualPrefix.yang");
+    }
+
+    /**
+     * Checks for the correct order of prefix in import.
+     */
+    @Test(expected = ParserException.class)
+    public void processImportInvalidOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ImportInvalidOrder.yang");
+    }
+
+    /**
+     * Checks if import listener updates the data model tree.
+     */
+    @Test
+    public void processImportValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ImportValidEntry.yang");
+
+        // Checks for the revision value in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getRevision(), is("2015-02-03"));
+        // Checks for the prefix id in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getPrefixId(), is("On2"));
+        // Checks for the module name in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getModuleName(), is("ietf"));
+    }
+
+    /**
+     * Checks if optional parameter revision is not mandatory in import.
+     */
+    @Test
+    public void processImportWithoutRevision() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ImportWithoutRevision.yang");
+
+        // Checks for the prefix id in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getPrefixId(), is("On2"));
+        // Checks for the module name in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getModuleName(), is("ietf"));
+    }
+
+    /**
+     * Checks if multiple imports are allowed.
+     */
+    @Test()
+    public void processImportMultipleInstance() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ImportMultipleInstance.yang");
+
+        // Checks for the prefix id in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getPrefixId(), is("On2"));
+        // Checks for the module name in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getModuleName(), is("ietf"));
+
+        // Checks for the prefix id in data model tree.
+        assertThat(((YangModule) node).getImportList().get(1).getPrefixId(), is("On3"));
+        // Checks for the module name in data model tree.
+        assertThat(((YangModule) node).getImportList().get(1).getModuleName(), is("itut"));
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing include listener functionality.
+ */
+public class IncludeListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if include listener with ; is valid and updates the data
+     * model tree.
+     */
+    @Test
+    public void processIncludeWithStmtend() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeWithStmtend.yang");
+
+        // Checks for the sub module name in data model tree.
+        assertThat(((YangModule) node).getIncludeList().get(0).getSubModuleName(), is("itut"));
+    }
+
+    /**
+     * Checks if include listener with braces and without revision date is valid
+     * and updates the data model tree.
+     */
+    @Test
+    public void processIncludeWithEmptyBody() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeWithEmptyBody.yang");
+
+        // Checks for the sub module name in data model tree.
+        assertThat(((YangModule) node).getIncludeList().get(0).getSubModuleName(), is("itut"));
+    }
+
+    /**
+     * Checks if include listener with braces and with revision date is valid
+     * and updates the data model tree.
+     */
+    @Test
+    public void processIncludeWithDate() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeWithDate.yang");
+
+        // Checks for the sub module name in data model tree.
+        assertThat(((YangModule) node).getIncludeList().get(0).getSubModuleName(), is("itut"));
+        assertThat(((YangModule) node).getIncludeList().get(0).getRevision(), is("2016-02-03"));
+    }
+
+    /**
+     * Checks if include has more than one occurrence.
+     */
+    @Test
+    public void processIncludeMultiInstance() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeMultiInstance.yang");
+
+        // Checks for the sub module name in data model tree.
+        assertThat(((YangModule) node).getIncludeList().get(0).getSubModuleName(), is("itut"));
+        assertThat(((YangModule) node).getIncludeList().get(0).getRevision(), is("2016-02-03"));
+        assertThat(((YangModule) node).getIncludeList().get(1).getSubModuleName(), is("sdn"));
+        assertThat(((YangModule) node).getIncludeList().get(1).getRevision(), is("2014-02-03"));
+    }
+
+    /**
+     * Checks if include and import can come in any order.
+     */
+    @Test
+    public void processIncludeImportAnyOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeImportAnyOrder.yang");
+
+        // Checks for the sub module name in data model tree.
+        assertThat(((YangModule) node).getIncludeList().get(0).getSubModuleName(), is("itut"));
+        assertThat(((YangModule) node).getIncludeList().get(0).getRevision(), is("2016-02-03"));
+        assertThat(((YangModule) node).getIncludeList().get(1).getSubModuleName(), is("sdn"));
+        assertThat(((YangModule) node).getIncludeList().get(1).getRevision(), is("2014-02-03"));
+    }
+
+    /**
+     * Checks if syntax of Include is not correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processIncludeInvalidSyntax() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeInvalidSyntax.yang");
+    }
+
+    /**
+     * Checks if syntax of revision date in Include is not correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processIncludeInvalidDateSyntax() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/IncludeInvalidDateSyntax.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangNodeType;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing module listener functionality.
+ */
+public class ModuleListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if module listener updates the data model root node.
+     */
+    @Test
+    public void processModuleValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ModuleValidEntry.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.MODULE_NODE));
+
+        // Check whether the module name is set correctly.
+        YangModule yangNode = (YangModule) node;
+        assertThat(yangNode.getName(), is("Test"));
+    }
+
+    /**
+     * Checks if module name is set correctly.
+     */
+    @Test(expected = ParserException.class)
+    public void processModuleInvalidEntryTest() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/ModuleWithInvalidIdentifier.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing namespace listener functionality.
+ */
+public class NamespaceListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks that value of namespace shouldn't have invalid spaces.
+     */
+    @Test(expected = ParserException.class)
+    public void processNamespaceWithInvalidSpaces() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/NamespaceWithInvalidSpaces.yang");
+    }
+
+    /**
+     * Checks if namespace with double quotes is allowed.
+     */
+    @Test()
+    public void processNamespaceInDoubleQuotes() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/NamespaceInDoubleQuotes.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getNameSpace().getUri(), is("\"urn:ietf:params:xml:ns:yang:ietf-ospf\""));
+    }
+
+    /**
+     * Checks if namespace without double quotes is allowed.
+     */
+    @Test()
+    public void processNamespaceWithoutQuotes() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/NamespaceWithoutQuotes.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getNameSpace().getUri(), is("urn:ietf:params:xml:ns:yang:ietf-ospf"));
+    }
+
+    /**
+     * Checks if namespace is present only once.
+     */
+    @Test(expected = ParserException.class)
+    public void processNamespaceDualEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/NamespaceDualEntry.yang");
+    }
+
+    /**
+     * Checks if mandatory parameter namespace is present.
+     */
+    @Test(expected = ParserException.class)
+    public void processNamespaceNoEntryTest() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/NamespaceNoEntryTest.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing organization listener functionality.
+ */
+public class OrganizationListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if organization listener updates the data model tree.
+     */
+    @Test
+    public void processOrganizationValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/OrganizationValidEntry.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getOrganization(), is("\"IETF SPRING Working Group\""));
+    }
+
+    /**
+     * Checks that organization must be present only once.
+     */
+    @Test(expected = ParserException.class)
+    public void processOrganizationDualEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/OrganizationDualEntry.yang");
+    }
+
+    /**
+     * Checks if organization entry syntax is correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processOrganizationMissingValue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/OrganizationMissingValue.yang");
+    }
+
+    /**
+     * Checks if organization and namespace is present in correct order.
+     */
+    @Test(expected = ParserException.class)
+    public void processOrganizationInvalidOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/OrganizationInvalidOrder.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing prefix listener functionality.
+ */
+public class PrefixListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if value of prefix is correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixInvalidValue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixInvalidValue.yang");
+    }
+
+    /**
+     * Checks if prefix listener updates the data model tree.
+     */
+    @Test
+    public void processPrefixValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixValidEntry.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getPrefix(), is("On"));
+    }
+
+    /**
+     * Checks that prefix should be present just once.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixDualEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixDualEntry.yang");
+    }
+
+    /**
+     * Checks if prefix syntax is followed.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixMissingValue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixMissingValue.yang");
+    }
+
+    /**
+     * Checks that exception should be reported if prefix is missing.
+     */
+    @Test(expected = ParserException.class)
+    public void processPrefixOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/PrefixOrder.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing revision date listener functionality.
+ */
+public class RevisionDateListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if revision date syntax is correct in include.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionDateInvalidSyntaxAtInclude() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionDateInvalidSyntaxAtInclude.yang");
+    }
+
+    /**
+     * Checks if revision date syntax is correct in import.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionDateInvalidSyntaxAtImport() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionDateInvalidSyntaxAtImport.yang");
+    }
+
+    /**
+     * Checks revision date should not be in quotes inside include.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionDateInQuotesAtInclude() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionDateInQuotesAtInclude.yang");
+    }
+
+    /**
+     * Checks revision date should not be in quotes inside import.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionDateInQuotesAtImport() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionDateInQuotesAtImport.yang");
+    }
+
+    /**
+     * Checks if revision date follows YYYY-MM-DD format.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionDateInvalidFormat() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionDateInvalidFormat.yang");
+    }
+
+    /**
+     * Checks if revision date listener updates the data model tree.
+     */
+    @Test
+    public void processRevisionDateValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionDateValidEntry.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getImportList().get(0).getRevision(), is("2015-02-03"));
+        assertThat(((YangModule) node).getIncludeList().get(0).getRevision(), is("2016-02-03"));
+        assertThat(((YangModule) node).getIncludeList().get(1).getRevision(), is("2014-02-03"));
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing revision listener functionality.
+ */
+public class RevisionListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if revision doesn't have optional parameters "revision and
+     * description".
+     */
+    @Test
+    public void processRevisionNoOptionalParameter() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionNoOptionalParameter.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getRevision().getRevDate(), is("2016-02-03"));
+    }
+
+    /**
+     * Checks if the syntax of revision is correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionInValidSyntax() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionInValidSyntax.yang");
+    }
+
+    /**
+     * Checks if the correct order is followed.
+     */
+    @Test(expected = ParserException.class)
+    public void processRevisionInValidOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/RevisionInValidOrder.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.datamodel.YangNodeType;
+import org.onosproject.yangutils.datamodel.YangSubModule;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing submodule listener functionality.
+ */
+public class SubModuleListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if the sub module listeners updates the data model tree.
+     */
+    @Test
+    public void processSubModuleValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/SubModuleValidEntry.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangSubModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.SUB_MODULE_NODE));
+
+        YangSubModule yangNode = (YangSubModule) node;
+        // Check whether the module name is set correctly.
+        assertThat(yangNode.getName(), is("Test"));
+        // Checks for the version value in data model tree.
+        assertThat(yangNode.getVersion(), is((byte) 1));
+        // Checks identifier of belongsto in data model tree.
+        assertThat(yangNode.getBelongsTo().getBelongsToModuleName(), is("ONOS"));
+        // Checks for the version value in data model tree.
+        assertThat(yangNode.getBelongsTo().getPrefix(), is("On1"));
+    }
+
+    /**
+     * Checks if the yang version and belongs to can come in any order in sub
+     * module.
+     */
+    @Test
+    public void processSubModuleOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/SubModuleOrder.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangSubModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.SUB_MODULE_NODE));
+
+        YangSubModule yangNode = (YangSubModule) node;
+        // Check whether the module name is set correctly.
+        assertThat(yangNode.getName(), is("Test"));
+        // Checks for the version value in data model tree.
+        assertThat(yangNode.getVersion(), is((byte) 1));
+        // Checks identifier of belongsto in data model tree.
+        assertThat(yangNode.getBelongsTo().getBelongsToModuleName(), is("ONOS"));
+        // Checks for the version value in data model tree.
+        assertThat(yangNode.getBelongsTo().getPrefix(), is("On1"));
+    }
+
+    /**
+     * Checks if yang version is optional.
+     */
+    @Test
+    public void processSubModuleWithoutVersion() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/SubModuleWithoutVersion.yang");
+
+        // Check whether the data model tree returned is of type module.
+        assertThat((node instanceof YangSubModule), is(true));
+
+        // Check whether the node type is set properly to module.
+        assertThat(node.getNodeType(), is(YangNodeType.SUB_MODULE_NODE));
+
+        YangSubModule yangNode = (YangSubModule) node;
+        // Check whether the module name is set correctly.
+        assertThat(yangNode.getName(), is("Test"));
+        // Checks identifier of belongsto in data model tree.
+        assertThat(yangNode.getBelongsTo().getBelongsToModuleName(), is("ONOS"));
+        // Checks for the version value in data model tree.
+        assertThat(yangNode.getBelongsTo().getPrefix(), is("On1"));
+    }
+
+    /**
+     * Checks if sub module name is correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processSubModuleInvalidName() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/SubModuleInvalidName.yang");
+    }
+
+    /**
+     * Checks if sub module has invalid modules construct eg namespace.
+     */
+    @Test(expected = ParserException.class)
+    public void processSubModuleWithNamespace() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/SubModuleWithNamespace.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.impl.listeners;
+
+import org.junit.Test;
+import org.onosproject.yangutils.datamodel.YangModule;
+import org.onosproject.yangutils.datamodel.YangNode;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
+
+import java.io.IOException;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test cases for testing version listener functionality.
+ */
+public class VersionListenerTest {
+
+    private final YangUtilsParserManager manager = new YangUtilsParserManager();
+
+    /**
+     * Checks if value of version is correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processVersionInvalidValue() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/VersionInvalidValue.yang");
+    }
+
+    /**
+     * Checks if version listener updates the data model tree.
+     */
+    @Test
+    public void processVersionValidEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/VersionValidEntry.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getVersion(), is((byte) 1));
+    }
+
+    /**
+     * Checks if version which is optional paramater is not present.
+     */
+    @Test
+    public void processVersionNotPresent() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/VersionNotPresent.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getVersion(), is((byte) 0));
+    }
+
+    /**
+     * Checks that version should be present only once.
+     */
+    @Test(expected = ParserException.class)
+    public void processVersionDualEntry() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/VersionDualEntry.yang");
+    }
+
+    /**
+     * Checks if version can appear in any order in module header.
+     */
+    @Test
+    public void processVersionOrder() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/VersionOrder.yang");
+
+        // Checks for the version value in data model tree.
+        assertThat(((YangModule) node).getVersion(), is((byte) 1));
+    }
+
+    /**
+     * Checks if sytax of version entry is not correct.
+     */
+    @Test(expected = ParserException.class)
+    public void processVersionInvalidSyntax() throws IOException, ParserException {
+
+        YangNode node = manager.getDataModel("src/test/resources/VersionInvalidSyntax.yang");
+    }
+}
\ No newline at end of file

+/*
+ * Copyright 2016 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.yangutils.parser.parseutils;
+
+import org.junit.Test;
+import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
+
+import static org.hamcrest.core.Is.is;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Test case for testing listener error message construction util.
+ */
+public class ListenerErrorMessageConstructionTest {
+
+    /**
+     * Checks for error message construction with parsable data type name.
+     */
+    @Test
+    public void checkErrorMsgConstructionWithName() {
+
+        // Create an test error message
+        String testErrorMessage = ListenerErrorMessageConstruction
+                .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER, ParsableDataType.CONTACT_DATA,
+                                               "Test Instance", ListenerErrorLocation.ENTRY);
+
+        // Check message.
+        assertThat(testErrorMessage, is("Internal parser error detected: Invalid holder for contact "
+                + "\"Test Instance\" before processing."));
+    }
+
+    /**
+     * Checks for error message construction without parsable data type name.
+     */
+    @Test
+    public void checkErrorMsgConstructionWithoutName() {
+
+        // Create an test error message
+        String testErrorMessage = ListenerErrorMessageConstruction
+                .constructListenerErrorMessage(ListenerErrorType.INVALID_HOLDER, ParsableDataType.CONTACT_DATA,
+                                               "Test Instance", ListenerErrorLocation.ENTRY);
+
+        // Check message.
+        assertThat(testErrorMessage,
+                   is("Internal parser error detected: Invalid holder for contact \"Test Instance\""
+                           + " before processing."));
+    }
+
+    /**
+     * Checks for extended error message construction with parsable data type name.
+     */
+    @Test
+    public void checkExtendedErrorMsgConstructionWithName() {
+
+        // Create an test error message
+        String testErrorMessage = ListenerErrorMessageConstruction
+                .constructExtendedListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                       ParsableDataType.CONTACT_DATA, "Test Instance",
+                                                       ListenerErrorLocation.ENTRY, "Extended Information");
+
+        // Check message.
+        assertThat(testErrorMessage,
+                   is("Internal parser error detected: Invalid holder for contact \"Test Instance\""
+                           + " before processing.\n" + "Error Information: Extended Information"));
+    }
+
+    /**
+     * Checks for extended error message construction without parsable data type name.
+     */
+    @Test
+    public void checkExtendedErrorMsgConstructionWithoutName() {
+
+        // Create an test error message
+        String testErrorMessage = ListenerErrorMessageConstruction
+                .constructExtendedListenerErrorMessage(ListenerErrorType.INVALID_HOLDER,
+                                                       ParsableDataType.CONTACT_DATA, "",
+                                                       ListenerErrorLocation.ENTRY, "Extended Information");
+
+        // Check message.
+        assertThat(testErrorMessage, is("Internal parser error detected: Invalid holder for contact"
+                + " before processing.\n" + "Error Information: Extended Information"));
+    }
+}
\ No newline at end of file

@@ -16,74 +16,80 @@
 
 package org.onosproject.yangutils.parser.parseutils;
 
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.onosproject.yangutils.datamodel.YangRevision;
+import org.onosproject.yangutils.parser.ParsableDataType;
+import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerError;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
+import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
 import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
 
-import static org.hamcrest.core.Is.is;
-import static org.junit.Assert.assertThat;
-
 /**
  * Test case for testing listener validation util.
  */
 public class ListenerValidationTest {
 
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
     /**
-     * This test case checks in case error pre-exists, listener validate
-     * function returns true.
+     * Checks for exception in case parsable stack is empty while validating for
+     * not empty scenario.
      */
     @Test
-    public void listenerValidationErrorExists() {
+    public void validateStackIsNotEmptyForEmptyStack() {
+
+        String expectedError = ListenerErrorMessageConstruction
+                .constructListenerErrorMessage(ListenerErrorType.MISSING_HOLDER, ParsableDataType.YANGBASE_DATA, "",
+                        ListenerErrorLocation.EXIT);
 
-        // Create an test error.
-        ListenerError testError = new ListenerError();
-        testError.setErrorFlag(true);
-        testError.setErrorMsg("Test Error");
+        // Get the exception occurred during parsing.
+        thrown.expect(ParserException.class);
+        thrown.expectMessage(expectedError);
 
         // Create test walker and assign test error to it.
         TreeWalkListener testWalker = new TreeWalkListener();
-        testWalker.setErrorInformation(testError);
-
-        // Create a temporary node of parsable.
-        YangRevision tmpNode = new YangRevision();
-        testWalker.getParsedDataStack().push(tmpNode);
-
-        boolean errorFlag = ListenerValidation.preValidation(testWalker, "ErrorTest");
 
-        /**
-         * Check for the values set in syntax error function. If not set properly
-         * report an assert.
-         */
-        assertThat(errorFlag, is(true));
+        ListenerValidation.checkStackIsNotEmpty(testWalker, ListenerErrorType.MISSING_HOLDER,
+                ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.EXIT);
     }
 
     /**
-     * This test case checks in case parsable stack is empty, listener validate
-     * function returns true.
+     * Checks if there is no exception in case parsable stack is not empty while validating
+     * for not empty scenario.
      */
     @Test
-    public void listenerValidationEmptyStack() {
+    public void validateStackIsNotEmptyForNonEmptyStack() {
 
         // Create test walker and assign test error to it.
         TreeWalkListener testWalker = new TreeWalkListener();
 
-        boolean errorFlag = ListenerValidation.preValidation(testWalker, "ErrorTest");
+        // Create a temporary node of parsable.
+        YangRevision tmpNode = new YangRevision();
+        testWalker.getParsedDataStack().push(tmpNode);
 
-        /**
-         * Check for the values set in syntax error function. If not set properly
-         * report an assert.
-         */
-        assertThat(errorFlag, is(true));
+        ListenerValidation.checkStackIsNotEmpty(testWalker, ListenerErrorType.MISSING_HOLDER,
+                                                ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.EXIT);
     }
 
     /**
-     * This test case checks in case of error doesn't pre-exists and stack is,
-     * non empty, listener validate function returns false.
+     * Checks for exception in case parsable stack is not empty while validating
+     * for empty scenario.
      */
     @Test
-    public void listenerValidationNoErrorNotExists() {
+    public void validateStackIsEmptyForNonEmptyStack() {
+
+        String expectedError = ListenerErrorMessageConstruction
+                .constructListenerErrorMessage(ListenerErrorType.MISSING_HOLDER, ParsableDataType.YANGBASE_DATA, "",
+                        ListenerErrorLocation.EXIT);
+
+        // Get the exception occurred during parsing.
+        thrown.expect(ParserException.class);
+        thrown.expectMessage(expectedError);
 
         // Create test walker and assign test error to it.
         TreeWalkListener testWalker = new TreeWalkListener();
@@ -92,12 +98,21 @@ public class ListenerValidationTest {
         YangRevision tmpNode = new YangRevision();
         testWalker.getParsedDataStack().push(tmpNode);
 
-        boolean errorFlag = ListenerValidation.preValidation(testWalker, "ErrorTest");
+        ListenerValidation.checkStackIsEmpty(testWalker, ListenerErrorType.MISSING_HOLDER,
+                                             ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.EXIT);
+    }
 
     /**
-         * Check for the values set in syntax error function. If not set properly
-         * report an assert.
+     * Checks if there is no exception in case parsable stack is empty while validating
+     * for empty scenario.
      */
-        assertThat(errorFlag, is(false));
+    @Test
+    public void validateStackIsEmptyForEmptyStack() {
+
+        // Create test walker and assign test error to it.
+        TreeWalkListener testWalker = new TreeWalkListener();
+
+        ListenerValidation.checkStackIsEmpty(testWalker, ListenerErrorType.MISSING_HOLDER,
+                                             ParsableDataType.YANGBASE_DATA, "", ListenerErrorLocation.EXIT);
     }
 }
\ No newline at end of file

@@ -14,29 +14,26 @@
  * limitations under the License.
  */
 
-package org.onosproject.yangutils.parser.impl.parseutils;
+package org.onosproject.yangutils.parser.parseutils;
 
 import org.antlr.v4.runtime.ANTLRFileStream;
 import org.antlr.v4.runtime.ANTLRInputStream;
 import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.tree.ParseTree;
-import org.junit.After;
-import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangLexer;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
+import org.onosproject.yangutils.parser.impl.CustomExceptionMatcher;
 import org.onosproject.yangutils.parser.impl.YangUtilsParserManager;
 import org.onosproject.yangutils.parser.impl.parserutils.ParseTreeErrorListener;
 
 import java.io.BufferedWriter;
 import java.io.File;
-import java.io.FileWriter;
 import java.io.IOException;
 
-import static org.hamcrest.core.Is.is;
-import static org.junit.Assert.assertThat;
-
 /**
  * Test case for testing parse tree error listener.
  */
@@ -46,31 +43,16 @@ public class ParseTreeErrorListenerTest {
     File file;
     BufferedWriter out;
 
-    @Before
-    public void setUp() throws Exception {
-        file = new File("demo.yang");
-        out = new BufferedWriter(new FileWriter(file));
-    }
-    @After
-    public void tearDown() throws Exception {
-        file.delete();
-    }
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
 
     /**
-     * This test case checks whether the error received from parser is correctly
-     * handled.
+     * Checks that no exception is generated for YANG file with valid syntax.
      */
     @Test
-    public void syntaxErrorValidationTest() throws IOException {
-
-        out.write("module ONOS {\n");
-        out.write("yang-version 1\n");
-        out.write("namespace urn:ietf:params:xml:ns:yang:ietf-ospf;\n");
-        out.write("prefix On;\n");
-        out.write("}\n");
-        out.close();
+    public void checkValidYangFileForNoSyntaxError() throws IOException {
 
-        ANTLRInputStream input = new ANTLRFileStream("demo.yang");
+        ANTLRInputStream input = new ANTLRFileStream("src/test/resources/YangFileWithoutSyntaxError.yang");
 
         // Create a lexer that feeds off of input char stream.
         GeneratedYangLexer lexer = new GeneratedYangLexer(input);
@@ -86,15 +68,34 @@ public class ParseTreeErrorListenerTest {
         parser.addErrorListener(parseTreeErrorListener);
         // Begin parsing YANG file and generate parse tree.
         ParseTree tree = parser.yangfile();
-        // Get the exception occurred during parsing.
-        ParserException parserException = parseTreeErrorListener.getParserException();
+    }
 
     /**
-         * Check for the values set in syntax error function. If not set properly
-         * report an assert.
+     * Checks that exception is generated for YANG file with invalid syntax.
      */
-        assertThat(parseTreeErrorListener.isExceptionFlag(), is(true));
-        assertThat(parserException.getLineNumber(), is(3));
-        assertThat(parserException.getCharPositionInLine(), is(0));
+    @Test
+    public void checkInvalidYangFileForSyntaxError() throws IOException {
+
+        // Get the exception occurred during parsing.
+        thrown.expect(ParserException.class);
+        thrown.expect(CustomExceptionMatcher.errorLocation(3, 0));
+        thrown.expectMessage("no viable alternative at input 'yang-version 1\\nnamespace'");
+
+        ANTLRInputStream input = new ANTLRFileStream("src/test/resources/YangFileWithSyntaxError.yang");
+
+        // Create a lexer that feeds off of input char stream.
+        GeneratedYangLexer lexer = new GeneratedYangLexer(input);
+        // Create a buffer of tokens pulled from the lexer.
+        CommonTokenStream tokens = new CommonTokenStream(lexer);
+        // Create a parser that feeds off the tokens buffer.
+        GeneratedYangParser parser = new GeneratedYangParser(tokens);
+        // Remove console error listener.
+        parser.removeErrorListeners();
+        // Create instance of customized error listener.
+        ParseTreeErrorListener parseTreeErrorListener = new ParseTreeErrorListener();
+        // Add customized error listener to catch errors during parsing.
+        parser.addErrorListener(parseTreeErrorListener);
+        // Begin parsing YANG file and generate parse tree.
+        ParseTree tree = parser.yangfile();
     }
 }
\ No newline at end of file

+submodule Test {
+yang-version 1;
+belongs-to ONOS {
+prefix On1;
+prefix On2;
+}
+}
+

+submodule Test {
+yang-version 1;
+belongs-to ONOS {
+prefix On1;
+}
+}

+submodule Test {
+yang-version 1;
+belongs-to ONOS {
+}
+}
+

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+organization "IETF SPRING Working Group";
+contact "WG List";
+contact "Invalid";
+}
+

+module Test {
+yang-version 1;
+contact "Test";
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+organization "IETF SPRING Working Group";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+organization "IETF SPRING Working Group";
+contact "WG List:  <mailto:spring@ietf.org>
+Editor:    Stephane Litkowski
+           <mailto:stephane.litkowski@orange.com>";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+organization "IETF SPRING Working Group";
+contact;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+revision-date 2015-02-03;
+prefix On1;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+import itut {
+prefix On3;
+revision-date 2016-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On1;
+prefix On2;
+revision-date 2015-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+revision-date 2015-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+include itut {
+revision-date 2016-02-03;
+}
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 16-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut; {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut;
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+}

+module Test:Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+namespace urn:ietf:params:xml:ns:yang:ietf-segment-routing;
+prefix On;
+}

+module Test {
+yang-version 1;
+namespace "urn:ietf:params:xml:ns:yang:ietf-ospf";
+prefix On;
+}

+module Test {
+yang-version 1;
+prefix On;
+}

+module Test {
+yang-version 1;
+namespace "urn:ietf:params:xml:ns:"
+             + "yang:ietf-segment-routing";
+prefix On;
+}

+module Test {
+yang-version 1;
+namespace "urn:ietf:params:xml :ns:yang:ietf-ospf";
+prefix On;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "IETF SPRING Working Group";
+organization "ITUT SPRING Working Group";
+}

+module Test {
+yang-version 1;
+organization "ONOS";
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut; {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization ;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "IETF SPRING Working Group";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+prefix On3;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix -On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix ;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+prefix test;
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+import ietf {
+prefix On2;
+revision-date "2015-02-03";
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date "2016-02-03";
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+import ietf {
+prefix On2;
+revision-date 15-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+import ietf {
+prefix On2;
+revision-date 2015/02/03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016/02/03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+revision 2016-02-03;
+include itut {
+revision-date 2016-02-03;
+}
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+contact "Test";
+organization "ONOS";
+revision;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix test;
+contact "Test";
+organization "ONOS";
+revision 2016-02-03;
+}

+submodule Test:Test {
+belongs-to ONOS {
+prefix On1;
+}
+yang-version 1;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+submodule Test {
+belongs-to ONOS {
+prefix On1;
+}
+yang-version 1;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+submodule Test {
+yang-version 1;
+belongs-to ONOS {
+prefix On1;
+}
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+submodule Test {
+belongs-to ONOS {
+prefix On1;
+}
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+submodule Test {
+yang-version 1;
+}

+submodule Test {
+belongs-to ONOS {
+prefix On1;
+}
+import ietf {
+prefix On2;
+revision-date 2015-02-03;
+}
+include itut {
+revision-date 2016-02-03;
+}
+include sdn {
+revision-date 2014-02-03;
+}
+contact "Test";
+organization "ONOS";
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+yang-version 1;
+}

+module Test {
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+yang-version ;
+}

+module Test {
+yang-version 2;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+}

+module Test {
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+}

+module Test {
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+yang-version 1;
+}

+module Test {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix On;
+}

+module Antlrtest {
+yang-version 1
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix Ant;
+}
+

+module Antlrtest {
+yang-version 1;
+namespace urn:ietf:params:xml:ns:yang:ietf-ospf;
+prefix Ant;
+}
+