[sonic-yang-mgmt]: sonic-yang-mgmt package for configuration validation. (#3861)

**- What I did**

#### wheel package Makefiles

- wheel package Makefiles for sonic-yang-mgmt package.

#### libyang Python APIs:
- python APIs based on libyang
- functions to load/merge yang models and Yang data files
- function to validate data trees based on Yang models
- functions to merge yang data files/trees
- add/set/delete node in schema and data trees
- find data/schema nodes from xpath from the Yang data/schema tree in memory
- find dependencies
- dump the data tree in json/xml

#### Extension of libyang Python APIs:
-- Cropping input config based on Yang Model.
-- Translate input config based on Yang Model.
-- rev Translate input config based on Yang Model.
-- Find xpath of port, portleaf and a yang list.
-- Find if node is key of a list while deletion if yes, then delete the parent.

Signed-off-by: Praveen Chaudhary pchaudhary@linkedin.com
Signed-off-by: Ping Mao pmao@linkedin.com

files/build_templates/sonic_debian_extension.j2

@@ -132,6 +132,11 @@ SONIC_YANG_MODEL_PY3_WHEEL_NAME=$(basename {{sonic_yang_models_py3_wheel_path}})
 sudo cp {{sonic_yang_models_py3_wheel_path}} $FILESYSTEM_ROOT/$SONIC_YANG_MODEL_PY3_WHEEL_NAME
 sudo https_proxy=$https_proxy LANG=C chroot $FILESYSTEM_ROOT pip3 install $SONIC_YANG_MODEL_PY3_WHEEL_NAME
 sudo rm -rf $FILESYSTEM_ROOT/$SONIC_YANG_MODEL_PY3_WHEEL_NAME
+# Install sonic-yang-mgmt Python package
+SONIC_YANG_MGMT_PY_WHEEL_NAME=$(basename {{sonic_yang_mgmt_py_wheel_path}})
+sudo cp {{sonic_yang_mgmt_py_wheel_path}} $FILESYSTEM_ROOT/$SONIC_YANG_MGMT_PY_WHEEL_NAME
+sudo https_proxy=$https_proxy LANG=C chroot $FILESYSTEM_ROOT pip install $SONIC_YANG_MGMT_PY_WHEEL_NAME
+sudo rm -rf $FILESYSTEM_ROOT/$SONIC_YANG_MGMT_PY_WHEEL_NAME
 
 # Install sonic-platform-common Python 2 package
 PLATFORM_COMMON_PY2_WHEEL_NAME=$(basename {{platform_common_py2_wheel_path}})

rules/sonic-yang-mgmt-py2.dep

@@ -0,0 +1,10 @@
+
+SPATH       := $($(SONIC_YANG_MGMT_PY)_SRC_PATH)
+DEP_FILES   := $(SONIC_COMMON_FILES_LIST) rules/sonic-yang-mgmt-py2.mk rules/sonic-yang-mgmt-py2.dep   
+DEP_FILES   += $(SONIC_COMMON_BASE_FILES_LIST)
+DEP_FILES   += $(shell git ls-files $(SPATH))
+
+$(SONIC_YANG_MGMT_PY)_CACHE_MODE  := GIT_CONTENT_SHA 
+$(SONIC_YANG_MGMT_PY)_DEP_FLAGS   := $(SONIC_COMMON_FLAGS_LIST)
+$(SONIC_YANG_MGMT_PY)_DEP_FILES   := $(DEP_FILES)
+

rules/sonic-yang-mgmt-py2.mk

@@ -0,0 +1,9 @@
+# sonic-yang-mgmt python2 wheel
+
+SONIC_YANG_MGMT_PY = sonic_yang_mgmt-1.0-py2-none-any.whl
+$(SONIC_YANG_MGMT_PY)_SRC_PATH = $(SRC_PATH)/sonic-yang-mgmt
+$(SONIC_YANG_MGMT_PY)_PYTHON_VERSION = 2
+$(SONIC_YANG_MGMT_PY)_DEBS_DEPENDS = $(LIBYANG)
+$(SONIC_YANG_MGMT_PY)_DEPENDS = $(SONIC_YANG_MODELS_PY3)
+
+SONIC_PYTHON_WHEELS += $(SONIC_YANG_MGMT_PY)

slave.mk

@@ -542,7 +542,6 @@ SONIC_TARGET_LIST += $(addprefix $(PYTHON_DEBS_PATH)/, $(SONIC_PYTHON_STDEB_DEBS
 $(addprefix $(PYTHON_WHEELS_PATH)/, $(SONIC_PYTHON_WHEELS)) : $(PYTHON_WHEELS_PATH)/% : .platform $$(addsuffix -install,$$(addprefix $(PYTHON_WHEELS_PATH)/,$$($$*_DEPENDS))) \
 			$(call dpkg_depend,$(PYTHON_WHEELS_PATH)/%.dep) \
 			$$(addsuffix -install,$$(addprefix $(DEBS_PATH)/,$$($$*_DEBS_DEPENDS)))
-
 	$(HEADER)
 
 	# Load the target deb from DPKG cache
@@ -786,7 +785,8 @@ $(addprefix $(TARGET_PATH)/, $(SONIC_INSTALLERS)) : $(TARGET_PATH)/% : \
         $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_PLATFORM_COMMON_PY2)) \
         $(addprefix $(PYTHON_WHEELS_PATH)/,$(REDIS_DUMP_LOAD_PY2)) \
         $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_PLATFORM_API_PY2)) \
-        $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_YANG_MODELS_PY3))
+        $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_YANG_MODELS_PY3)) \
+        $(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_YANG_MGMT_PY))
 	$(HEADER)
 	# Pass initramfs and linux kernel explicitly. They are used for all platforms
 	export debs_path="$(IMAGE_DISTRO_DEBS_PATH)"
@@ -818,6 +818,7 @@ $(addprefix $(TARGET_PATH)/, $(SONIC_INSTALLERS)) : $(TARGET_PATH)/% : \
 	export redis_dump_load_py2_wheel_path="$(addprefix $(PYTHON_WHEELS_PATH)/,$(REDIS_DUMP_LOAD_PY2))"
 	export install_debug_image="$(INSTALL_DEBUG_TOOLS)"
 	export sonic_yang_models_py3_wheel_path="$(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_YANG_MODELS_PY3))"
+	export sonic_yang_mgmt_py_wheel_path="$(addprefix $(PYTHON_WHEELS_PATH)/,$(SONIC_YANG_MGMT_PY))"
 	export multi_instance="false"
 
 	$(foreach docker, $($*_DOCKERS),\

src/sonic-yang-mgmt/AUTHORS.rst

@@ -0,0 +1,15 @@
+=======
+Credits
+=======
+
+Development Lead
+----------------
+
+LNOS-CODERS    <lnos-coders@linkedin.com>
+MSFT-LINUX-DEV <linuxnetdev@microsoft.com>
+
+Contributors
+------------
+
+Praveen Chaudhary      <pchaudhary@linkedin.com>
+Ping Mao               <pmao@linkedin.com>

src/sonic-yang-mgmt/LICENSE

@@ -0,0 +1,13 @@
+Copyright 2019 Microsoft, Inc
+
+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.

src/sonic-yang-mgmt/README.rst

@@ -0,0 +1,6 @@
+"
+This package includes python yang libraries which will be used with sonic utilities
+pacakge to validate the config. This python libraries are written on top of libyang
+and also provides functionality to translate the config from SONiC ConfigDB to SONiC
+YANG and vice-versa.
+"

src/sonic-yang-mgmt/setup.py

@@ -0,0 +1,98 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""The setup script."""
+
+from setuptools import setup, find_packages
+from setuptools.command.build_py import build_py
+from os import system, environ
+from sys import exit
+import pytest
+
+# find path of pkgs from os environment vars
+prefix = '../../'; debs = environ["IMAGE_DISTRO_DEBS_PATH"]
+wheels = environ["PYTHON_WHEELS_PATH"]
+wheels_path = '{}/{}'.format(prefix, wheels)
+deps_path = '{}/{}'.format(prefix, debs)
+# dependencies
+libyang = '{}/{}'.format(deps_path, environ["LIBYANG"])
+libyangCpp = '{}/{}'.format(deps_path, environ["LIBYANG_CPP"])
+libyangPy2 = '{}/{}'.format(deps_path, environ["LIBYANG_PY2"])
+libyangPy3 = '{}/{}'.format(deps_path, environ["LIBYANG_PY3"])
+sonicYangModels = '{}/{}'.format(wheels_path, environ["SONIC_YANG_MODELS_PY3"])
+
+# important reuirements parameters
+build_requirements = [libyang, libyangCpp, libyangPy2, libyangPy3, sonicYangModels,]
+
+setup_requirements = ['pytest-runner']
+
+test_requirements = ['pytest>=3']
+
+# read me
+with open('README.rst') as readme_file:
+    readme = readme_file.read()
+
+# class for prerequisites to build this package
+class pkgBuild(build_py):
+    """Custom Build PLY"""
+
+    def run (self):
+        #  install libyang and sonic_yang_models
+        for req in build_requirements:
+            if '.deb' in req:
+                pkg_install_cmd = "sudo dpkg -i {}".format(req)
+                if (system(pkg_install_cmd)):
+                    print("{} installation failed".format(req))
+                    exit(1)
+                else:
+                    print("{} installed".format(req))
+            elif '.whl' in req:
+                pkg_install_cmd = "pip3 install {}".format(req)
+                if (system(pkg_install_cmd)):
+                    print("{} installation failed".format(req))
+                    exit(1)
+                else:
+                    print("{} installed".format(req))
+
+        # run pytest for libyang python APIs
+        self.pytest_args = []
+        errno = pytest.main(self.pytest_args)
+        if (errno):
+            exit(errno)
+
+        # Continue usual build steps
+        build_py.run(self)
+
+setup(
+    cmdclass={
+        'build_py': pkgBuild,
+    },
+    author="lnos-coders",
+    author_email='lnos-coders@linkedin.com',
+    python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*',
+    classifiers=[
+        'Development Status :: 2 - Pre-Alpha',
+        'Intended Audience :: Developers',
+        'License :: OSI Approved :: GNU General Public License v3 (GPLv3)',
+        'Natural Language :: English',
+        "Programming Language :: Python :: 2",
+        'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+    ],
+    description="Package contains Python Library for YANG for sonic.",
+    tests_require = test_requirements,
+    license="GNU General Public License v3",
+    long_description=readme + '\n\n',
+    include_package_data=True,
+    keywords='sonic_yang_mgmt',
+    name='sonic_yang_mgmt',
+    py_modules=['sonic_yang', 'sonic_yang_ext'],
+    packages=find_packages(),
+    setup_requires=setup_requirements,
+    version='1.0',
+    zip_safe=False,
+)

src/sonic-yang-mgmt/sonic_yang.py

@@ -0,0 +1,659 @@
+import yang as ly
+import syslog
+
+from json import dump
+from glob import glob
+from sonic_yang_ext import SonicYangExtMixin, SonicYangException
+
+"""
+Yang schema and data tree python APIs based on libyang python
+Here, sonic_yang_ext_mixin extends funtionality of sonic_yang,
+i.e. it is mixin not parent class.
+"""
+class SonicYang(SonicYangExtMixin):
+
+    def __init__(self, yang_dir, debug=False):
+        self.yang_dir = yang_dir
+        self.ctx = None
+        self.module = None
+        self.root = None
+
+        # logging vars
+        self.SYSLOG_IDENTIFIER = "sonic_yang"
+        self.DEBUG = debug
+
+        # yang model files, need this map it to module
+        self.yangFiles = list()
+        # map from TABLE in config DB to container and module
+        self.confDbYangMap = dict()
+        # JSON format of yang model [similar to pyang conversion]
+        self.yJson = list()
+        # config DB json input, will be cropped as yang models
+        self.jIn = dict()
+        # YANG JSON, this is traslated from config DB json
+        self.xlateJson = dict()
+        # reverse translation from yang JSON, == config db json
+        self.revXlateJson = dict()
+        # below dict store the input config tables which have no YANG models
+        self.tablesWithOutYang = dict()
+
+        try:
+            self.ctx = ly.Context(yang_dir)
+        except Exception as e:
+            self.fail(e)
+
+        return
+
+    def __del__(self):
+        pass
+
+    def sysLog(self, debug=syslog.LOG_INFO, msg=None):
+
+        # log debug only if enabled
+        if self.DEBUG == False and debug == syslog.LOG_DEBUG:
+            return
+        syslog.openlog(self.SYSLOG_IDENTIFIER)
+        syslog.syslog(debug, msg)
+        syslog.closelog()
+
+        return
+
+    def fail(self, e):
+        print(e)
+        raise e
+
+    """
+    load_schema_module(): load a Yang model file
+    input:    yang_file - full path of a Yang model file
+    returns:  Exception if error
+    """
+    def _load_schema_module(self, yang_file):
+        try:
+            return self.ctx.parse_module_path(yang_file, ly.LYS_IN_YANG)
+        except Exception as e:
+            print("Failed to load yang module file: " + yang_file)
+            self.fail(e)
+
+    """
+    load_schema_module_list(): load all Yang model files in the list
+    input:    yang_files - a list of Yang model file full path
+    returns:  Exception if error
+    """
+    def _load_schema_module_list(self, yang_files):
+        for file in yang_files:
+             try:
+                 self._load_schema_module(file)
+             except Exception as e:
+                 self.fail(e)
+
+    """
+    load_schema_modules(): load all Yang model files in the directory
+    input:    yang_dir - the directory of the yang model files to be loaded
+    returns:  Exception if error
+    """
+    def _load_schema_modules(self, yang_dir):
+        py = glob(yang_dir+"/*.yang")
+        for file in py:
+            try:
+                self._load_schema_module(file)
+            except Exception as e:
+                self.fail(e)
+
+    """
+    load_schema_modules_ctx(): load all Yang model files in the directory to context: ctx
+    input:    yang_dir,  context
+    returns:  Exception if error, returrns context object if no error
+    """
+    def _load_schema_modules_ctx(self, yang_dir=None):
+        if not yang_dir:
+            yang_dir = self.yang_dir
+
+        ctx = ly.Context(yang_dir)
+
+        py = glob(yang_dir+"/*.yang")
+        for file in py:
+            try:
+                ctx.parse_module_path(str(file), ly.LYS_IN_YANG)
+            except Exception as e:
+                print("Failed to parse yang module file: " + file)
+                self.fail(e)
+
+        return ctx
+
+    """
+    load_data_file(): load a Yang data json file
+    input:    data_file - the full path of the yang json data file to be loaded
+    returns:  Exception if error
+    """
+    def _load_data_file(self, data_file):
+       try:
+           data_node = self.ctx.parse_data_path(data_file, ly.LYD_JSON, ly.LYD_OPT_CONFIG | ly.LYD_OPT_STRICT)
+       except Exception as e:
+           print("Failed to load data file: " + str(data_file))
+           self.fail(e)
+       else:
+           self.root = data_node
+
+    """
+    get module name from xpath
+    input:    path
+    returns:  module name
+    """
+    def _get_module_name(self, schema_xpath):
+        module_name = schema_xpath.split(':')[0].strip('/')
+        return module_name
+
+    """
+    get_module(): get module object from Yang module name
+    input:   yang module name
+    returns: Schema_Node object
+    """
+    def _get_module(self, module_name):
+        mod = self.ctx.get_module(module_name)
+        return mod
+
+    """
+    load_data_model(): load both Yang module fileis and data json files
+    input:   yang directory, list of yang files and list of data files (full path)
+    returns: returns (context, root) if no error,  or Exception if failed
+    """
+    def _load_data_model(self, yang_dir, yang_files, data_files, output=None):
+        if (self.ctx is None):
+            self.ctx = ly.Context(yang_dir)
+
+        try:
+            self._load_schema_module_list(yang_files)
+            if len(data_files) == 0:
+                return (self.ctx, self.root)
+
+            self._load_data_file(data_files[0])
+
+            for i in range(1, len(data_files)):
+                self._merge_data(data_files[i])
+        except Exception as e:
+            print("Failed to load data files")
+            self.fail(e)
+            return
+
+        if output is not None:
+            self._print_data_mem(output)
+
+        return (self.ctx, self.root)
+
+    """
+    print_data_mem():  print the data tree
+    input:  option:  "JSON" or "XML"
+    """
+    def _print_data_mem(self, option):
+        if (option == "JSON"):
+            mem = self.root.print_mem(ly.LYD_JSON, ly.LYP_WITHSIBLINGS | ly.LYP_FORMAT)
+        else:
+            mem = self.root.print_mem(ly.LYD_XML, ly.LYP_WITHSIBLINGS | ly.LYP_FORMAT)
+
+        return mem
+
+    """
+    save_data_file_json(): save the data tree in memory into json file
+    input: outfile - full path of the file to save the data tree to
+    """
+    def _save_data_file_json(self, outfile):
+        mem = self.root.print_mem(ly.LYD_JSON, ly.LYP_FORMAT)
+        with open(outfile, 'w') as out:
+            dump(mem, out, indent=4)
+
+    """
+    get_module_tree(): get yang module tree in JSON or XMAL format
+    input:   module name
+    returns: JSON or XML format of the input yang module schema tree
+    """
+    def _get_module_tree(self, module_name, format):
+        result = None
+
+        try:
+            module = self.ctx.get_module(str(module_name))
+        except Exception as e:
+            print("Cound not get module: " + str(module_name))
+            self.fail(e)
+        else:
+            if (module is not None):
+                if (format == "XML"):
+                    #libyang bug with format
+                    result = module.print_mem(ly.LYD_JSON, ly.LYP_FORMAT)
+                else:
+                    result = module.print_mem(ly.LYD_XML, ly.LYP_FORMAT)
+
+        return result
+
+    """
+    validate_data(): validate data tree
+    input:
+           node:   root of the data tree
+           ctx:    context
+    returns:  Exception if failed
+    """
+    def _validate_data(self, node=None, ctx=None):
+        if not node:
+            node = self.root
+
+        if not ctx:
+            ctx = self.ctx
+
+        try:
+            node.validate(ly.LYD_OPT_CONFIG, ctx)
+        except Exception as e:
+            self.fail(e)
+
+    """
+    validate_data_tree(): validate the data tree. (Public)
+    returns: Exception if failed
+    """
+    def validate_data_tree(self):
+        try:
+            self._validate_data(self.root, self.ctx)
+        except Exception as e:
+            print("Failed to validate data tree")
+            raise SonicYangException("Failed to validate data tree\n{}".\
+                format(str(e)))
+
+    """
+    find_parent_data_node():  find the parent node object
+    input:    data_xpath - xpath of the data node
+    returns:  parent node
+    """
+    def _find_parent_data_node(self, data_xpath):
+        if (self.root is None):
+            print("data not loaded")
+            return None
+        try:
+            data_node = self._find_data_node(data_xpath)
+        except Exception as e:
+            print("Failed to find data node from xpath: " + str(data_xpath))
+            self.fail(e)
+        else:
+            if data_node is not None:
+                return data_node.parent()
+
+        return None
+
+    """
+    get_parent_data_xpath():  find the parent data node's xpath
+    input:    data_xpath - xpathof the data node
+    returns:  - xpath of parent data node
+              - Exception if error
+    """
+    def _get_parent_data_xpath(self, data_xpath):
+        path=""
+        try:
+            data_node = self._find_parent_data_node(data_xpath)
+        except Exception as e:
+            print("Failed to find parent node from xpath: " + str(data_xpath))
+            self.fail(e)
+        else:
+            if  data_node is not None:
+                path = data_node.path()
+        return path
+
+    """
+    new_data_node(): create a new data node in the data tree
+    input:
+           xpath: xpath of the new node
+           value: value of the new node
+    returns:  new Data_Node object if success,  Exception if falied
+    """
+    def _new_data_node(self, xpath, value):
+        val = str(value)
+        try:
+            data_node = self.root.new_path(self.ctx, xpath, val, 0, 0)
+        except Exception as e:
+            print("Failed to add data node for path: " + str(xpath))
+            self.fail(e)
+        else:
+            return data_node
+
+    """
+    find_data_node():  find the data node from xpath
+    input:    data_xpath: xpath of the data node
+    returns   - Data_Node object if found
+              - None if not exist
+              - Exception if there is error
+    """
+    def _find_data_node(self, data_xpath):
+        try:
+            set = self.root.find_path(data_xpath)
+        except Exception as e:
+            print("Failed to find data node from xpath: " + str(data_xpath))
+            self.fail(e)
+        else:
+            if set is not None:
+                for data_node in set.data():
+                    if (data_xpath == data_node.path()):
+                        return data_node
+            return None
+    """
+    find_schema_node(): find the schema node from schema xpath
+        example schema xpath:
+        "/sonic-port:sonic-port/sonic-port:PORT/sonic-port:PORT_LIST/sonic-port:port_name"
+    input:    xpath of the node
+    returns:  Schema_Node oject or None if not found
+    """
+    def _find_schema_node(self, schema_xpath):
+        try:
+            schema_set = self.ctx.find_path(schema_xpath)
+            for schema_node in schema_set.schema():
+                if (schema_xpath == schema_node.path()):
+                    return schema_node
+        except Exception as e:
+             self.fail(e)
+             return None
+        else:
+             for schema_node in schema_set.schema():
+                 if schema_xapth == schema_node.path():
+                     return schema_node
+             return None
+    """
+    find_data_node_schema_xpath(): find the xpath of the schema node from data xpath
+      data xpath example:
+      "/sonic-port:sonic-port/PORT/PORT_LIST[port_name='Ethernet0']/port_name"
+    input:    data_xpath - xpath of the data node
+    returns:  - xpath of the schema node if success
+              - Exception if error
+    """
+    def _find_data_node_schema_xpath(self, data_xpath):
+        path = ""
+        try:
+            set = self.root.find_path(data_xpath)
+        except Exception as e:
+            self.fail(e)
+        else:
+            for data_node in set.data():
+                if data_xpath == data_node.path():
+                    return data_node.schema().path()
+            return path
+
+    """
+    add_node(): add a node to Yang schema or data tree
+    input:    xpath and value of the node to be added
+    returns:  Exception if failed
+    """
+    def _add_data_node(self, data_xpath, value):
+        try:
+            self._new_data_node(data_xpath, value)
+            #check if the node added to the data tree
+            self._find_data_node(data_xpath)
+        except Exception as e:
+            print("add_node(): Failed to add data node for xpath: " + str(data_xpath))
+            self.fail(e)
+
+    """
+    merge_data(): merge a data file to the existing data tree
+    input:    yang model directory and full path of the data json file to be merged
+    returns:  Exception if failed
+    """
+    def _merge_data(self, data_file, yang_dir=None):
+        #load all yang models to ctx
+        if not yang_dir:
+            yang_dir = self.yang_dir
+
+        try:
+            ctx = self._load_schema_modules_ctx(yang_dir)
+
+            #source data node
+            source_node = ctx.parse_data_path(str(data_file), ly.LYD_JSON, ly.LYD_OPT_CONFIG | ly.LYD_OPT_STRICT)
+
+            #merge
+            self.root.merge(source_node, 0)
+        except Exception as e:
+            self.fail(e)
+
+    """
+    _deleteNode(): delete a node from the schema/data tree, internal function
+    input:    xpath of the schema/data node
+    returns:  True - success   False - failed
+    """
+    def _deleteNode(self, xpath=None, node=None):
+        if node is None:
+            node = self._find_data_node(xpath)
+
+        if (node):
+            node.unlink()
+            dnode = self._find_data_node(xpath)
+            if (dnode is None):
+                #deleted node not found
+                return True
+            else:
+                print('Could not delete Node')
+                return False
+        else:
+            print("failed to find node, xpath: " + xpath)
+
+        return False
+
+    """
+    find_data_node_value():  find the value of a node from the data tree
+    input:    data_xpath of the data node
+    returns:  value string of the node
+    """
+    def _find_data_node_value(self, data_xpath):
+        output = ""
+        try:
+            data_node = self._find_data_node(data_xpath)
+        except Exception as e:
+            print("find_data_node_value(): Failed to find data node from xpath: {}".format(data_xpath))
+            self.fail(e)
+        else:
+            if (data_node is not None):
+                subtype = data_node.subtype()
+                if (subtype is not None):
+                    value = subtype.value_str()
+                    return value
+            return output
+
+    """
+    set the value of a node in the data tree
+    input:    xpath of the data node
+    returns:  Exception if failed
+    """
+    def _set_data_node_value(self, data_xpath, value):
+        try:
+            self.root.new_path(self.ctx, data_xpath, str(value), ly.LYD_ANYDATA_STRING, ly.LYD_PATH_OPT_UPDATE)
+        except Exception as e:
+            print("set data node value failed for xpath: " + str(data_xpath))
+            self.fail(e)
+
+    """
+    find_data_nodes(): find the set of nodes for the xpath
+    input:    xpath of the data node
+    returns:  list of xpath of the dataset
+    """
+    def _find_data_nodes(self, data_xpath):
+        list = []
+        node = self.root.child()
+        try:
+            node_set = node.find_path(data_xpath);
+        except Exception as e:
+            self.fail(e)
+        else:
+            if node_set is None:
+                raise Exception('data node not found')
+
+            for data_set in node_set.data():
+                data_set.schema()
+                list.append(data_set.path())
+            return list
+
+    """
+    find_schema_dependencies():  find the schema dependencies from schema xpath
+    input:    schema_xpath of the schema node
+    returns:  - list of xpath of the dependencies
+              - Exception if schema node not found
+    """
+    def _find_schema_dependencies(self, schema_xpath):
+        ref_list = []
+        try:
+            schema_node = self._find_schema_node(schema_xpath)
+        except Exception as e:
+            print("Cound not find the schema node from xpath: " + str(schema_xpath))
+            self.fail(e)
+            return ref_list
+
+        schema_node = ly.Schema_Node_Leaf(schema_node)
+        backlinks = schema_node.backlinks()
+        if backlinks.number() > 0:
+            for link in backlinks.schema():
+                print("backlink schema: {}".format(link.path()))
+                ref_list.append(link.path())
+        return ref_list
+
+    """
+    find_data_dependencies():   find the data dependencies from data xpath
+    input:    data_xpath - xpath of data node. (Public)
+    returns:  - list of xpath
+              - Exception if error
+    """
+    def find_data_dependencies(self, data_xpath):
+        ref_list = []
+        node = self.root
+        try:
+            data_node = self._find_data_node(data_xpath)
+        except Exception as e:
+            print("find_data_dependencies(): Failed to find data node from xpath: {}".format(data_xapth))
+            return ref_list
+
+        try:
+            value = str(self._find_data_node_value(data_xpath))
+
+            schema_node = ly.Schema_Node_Leaf(data_node.schema())
+            backlinks = schema_node.backlinks()
+            if backlinks.number() > 0:
+                for link in backlinks.schema():
+                     node_set = node.find_path(link.path())
+                     for data_set in node_set.data():
+                          data_set.schema()
+                          casted = data_set.subtype()
+                          if value == casted.value_str():
+                              ref_list.append(data_set.path())
+        except Exception as e:
+            print('Failed to find node or dependencies for {}'.format(data_xpath))
+            raise SonicYangException("Failed to find node or dependencies for \
+                {}\n{}".format(data_xpath, str(e)))
+
+        return ref_list
+
+    """
+    get_module_prefix:   get the prefix of a Yang module
+    input:    name of the Yang module
+    output:   prefix of the Yang module
+    """
+    def _get_module_prefix(self, module_name):
+        prefix = ""
+        try:
+            module = self._get_module(module_name)
+        except Exception as e:
+            self.fail(e)
+            return prefix
+        else:
+            return module.prefix()
+
+    """
+    str_to_type:   map string to type of node
+    input:    string
+    output:   type
+    """
+    def _str_to_type(self, type_str):
+           mapped_type = {
+                "LY_TYPE_DER":ly.LY_TYPE_DER,
+                "LY_TYPE_BINARY":ly.LY_TYPE_BINARY,
+                "LY_TYPE_BITS":ly.LY_TYPE_BITS,
+                "LY_TYPE_BOOL":ly.LY_TYPE_BOOL,
+                "LY_TYPE_DEC64":ly.LY_TYPE_DEC64,
+                "LY_TYPE_EMPTY":ly.LY_TYPE_EMPTY,
+                "LY_TYPE_ENUM":ly.LY_TYPE_ENUM,
+                "LY_TYPE_IDENT":ly.LY_TYPE_IDENT,
+                "LY_TYPE_INST":ly.LY_TYPE_INST,
+                "LY_TYPE_LEAFREF":ly.LY_TYPE_LEAFREF,
+                "LY_TYPE_STRING":ly.LY_TYPE_STRING,
+                "LY_TYPE_UNION":ly.LY_TYPE_UNION,
+                "LY_TYPE_INT8":ly.LY_TYPE_INT8,
+                "LY_TYPE_UINT8":ly.LY_TYPE_UINT8,
+                "LY_TYPE_INT16":ly.LY_TYPE_INT16,
+                "LY_TYPE_UINT16":ly.LY_TYPE_UINT16,
+                "LY_TYPE_INT32":ly.LY_TYPE_INT32,
+                "LY_TYPE_UINT32":ly.LY_TYPE_UINT32,
+                "LY_TYPE_INT64":ly.LY_TYPE_INT64,
+                "LY_TYPE_UINT64":ly.LY_TYPE_UINT64,
+                "LY_TYPE_UNKNOWN":ly.LY_TYPE_UNKNOWN
+           }
+
+           if type_str not in mapped_type:
+               return ly.LY_TYPE_UNKNOWN
+
+           return mapped_type[type_str]
+
+    def _get_data_type(self, schema_xpath):
+        try:
+            schema_node = self._find_schema_node(schema_xpath)
+        except Exception as e:
+            print("get_data_type(): Failed to find schema node from xpath: {}".format(schema_xpath))
+            self.fail(e)
+            return None
+
+        if (schema_node is not None):
+           return schema_node.subtype().type().base()
+
+        return ly.LY_TYPE_UNKNOWN
+
+    """
+    get_leafref_type:   find the type of node that leafref references to
+    input:    data_xpath - xpath of a data node
+    output:   type of the node this leafref references to
+    """
+    def _get_leafref_type(self, data_xpath):
+        data_node = self._find_data_node(data_xpath)
+        if (data_node is not None):
+            subtype = data_node.subtype()
+            if (subtype is not None):
+                if data_node.schema().subtype().type().base() != ly.LY_TYPE_LEAFREF:
+                    print("get_leafref_type() node type for data xpath: {} is not LEAFREF".format(data_xpath))
+                    return ly.LY_TYPE_UNKNOWN
+                else:
+                    return subtype.value_type()
+
+        return ly.LY_TYPE_UNKNOWN
+
+    """
+    get_leafref_path():   find the leafref path
+    input:    schema_xpath - xpath of a schema node
+    output:   path value of the leafref node
+    """
+    def _get_leafref_path(self, schema_xpath):
+        schema_node = self._find_schema_node(schema_xpath)
+        if (schema_node is not None):
+            subtype = schema_node.subtype()
+            if (subtype is not None):
+                if subtype.type().base() != ly.LY_TYPE_LEAFREF:
+                    return None
+                else:
+                    return subtype.type().info().lref().path()
+
+        return None
+
+    """
+    get_leafref_type_schema:   find the type of node that leafref references to
+    input:    schema_xpath - xpath of a schema node
+    output:   type of the node this leafref references to
+    """
+    def _get_leafref_type_schema(self, schema_xpath):
+        schema_node = self._find_schema_node(schema_xpath)
+        if (schema_node is not None):
+            subtype = schema_node.subtype()
+            if (subtype is not None):
+                if subtype.type().base() != ly.LY_TYPE_LEAFREF:
+                    return None
+                else:
+                    subtype.type().info().lref().path()
+                    target = subtype.type().info().lref().target()
+                    target_path = target.path()
+                    target_type = self._get_data_type(target_path)
+                    return target_type
+
+        return None

src/sonic-yang-mgmt/sonic_yang_ext.py

@@ -0,0 +1,756 @@
+# This script is used as extension of sonic_yang class. It has methods of
+# class sonic_yang. A separate file is used to avoid a single large file.
+
+from __future__ import print_function
+import yang as ly
+import re
+import syslog
+
+from json import dump, dumps, loads
+from xmltodict import parse
+from glob import glob
+
+"""
+This is the Exception thrown out of all public function of this class.
+"""
+class SonicYangException(Exception):
+    pass
+
+# class sonic_yang methods, use mixin to extend sonic_yang
+class SonicYangExtMixin:
+
+    """
+    load all YANG models, create JSON of yang models. (Public function)
+    """
+    def loadYangModel(self):
+
+        try:
+            # get all files
+            self.yangFiles = glob(self.yang_dir +"/*.yang")
+            # load yang modules
+            for file in self.yangFiles:
+                m = self._load_schema_module(file)
+                if m is not None:
+                    self.sysLog(msg="module: {} is loaded successfully".format(m.name()))
+                else:
+                    raise(Exception("Could not load module {}".format(file)))
+
+            # keep only modules name in self.yangFiles
+            self.yangFiles = [f.split('/')[-1] for f in self.yangFiles]
+            self.yangFiles = [f.split('.')[0] for f in self.yangFiles]
+            print('Loaded below Yang Models')
+            print(self.yangFiles)
+
+            # load json for each yang model
+            self._loadJsonYangModel()
+            # create a map from config DB table to yang container
+            self._createDBTableToModuleMap()
+
+        except Exception as e:
+            print("Yang Models Load failed")
+            raise SonicYangException("Yang Models Load failed\n{}".format(str(e)))
+
+        return True
+
+    """
+    load JSON schema format from yang models
+    """
+    def _loadJsonYangModel(self):
+
+        try:
+            for f in self.yangFiles:
+                m = self.ctx.get_module(f)
+                if m is not None:
+                    xml = m.print_mem(ly.LYD_JSON, ly.LYP_FORMAT)
+                    self.yJson.append(parse(xml))
+                    self.sysLog(msg="Parsed Json for {}".format(m.name()))
+        except Exception as e:
+            raise e
+
+        return
+
+    """
+    Create a map from config DB tables to container in yang model
+    This module name and topLevelContainer are fetched considering YANG models are
+    written using below Guidelines:
+    https://github.com/Azure/SONiC/blob/master/doc/mgmt/SONiC_YANG_Model_Guidelines.md.
+    """
+    def _createDBTableToModuleMap(self):
+
+        for j in self.yJson:
+            # get module name
+            moduleName = j['module']['@name']
+            # get top level container
+            topLevelContainer = j['module'].get('container')
+            # if top level container is none, this is common yang files, which may
+            # have definitions. Store module.
+            if topLevelContainer is None:
+                self.confDbYangMap[moduleName] = j['module']
+                continue
+
+            # top level container must exist for rest of the yang files and it should
+            # have same name as module name.
+            assert topLevelContainer['@name'] == moduleName
+
+            # Each container inside topLevelContainer maps to a sonic config table.
+            container = topLevelContainer['container']
+            # container is a list
+            if isinstance(container, list):
+                for c in container:
+                    self.confDbYangMap[c['@name']] = {
+                        "module" : moduleName,
+                        "topLevelContainer": topLevelContainer['@name'],
+                        "container": c
+                        }
+            # container is a dict
+            else:
+                self.confDbYangMap[container['@name']] = {
+                    "module" : moduleName,
+                    "topLevelContainer": topLevelContainer['@name'],
+                    "container": container
+                    }
+        return
+
+    """
+    Get module, topLevelContainer(TLC) and json container for a config DB table
+    """
+    def _getModuleTLCcontainer(self, table):
+        cmap = self.confDbYangMap
+        m = cmap[table]['module']
+        t = cmap[table]['topLevelContainer']
+        c = cmap[table]['container']
+        return m, t, c
+
+    """
+    Crop config as per yang models,
+    This Function crops from config only those TABLEs, for which yang models is
+    provided. The Tables without YANG models are stored in
+    self.tablesWithOutYangModels.
+    """
+    def _cropConfigDB(self, croppedFile=None):
+
+        for table in self.jIn.keys():
+            if table not in self.confDbYangMap:
+                # store in tablesWithOutYang
+                self.tablesWithOutYang[table] = self.jIn[table]
+                del self.jIn[table]
+
+        if len(self.tablesWithOutYang):
+            print("Note: Below table(s) have no YANG models:")
+            for table in self.tablesWithOutYang.keys():
+                print(unicode(table), end=", ")
+            print()
+
+        if croppedFile:
+            with open(croppedFile, 'w') as f:
+                dump(self.jIn, f, indent=4)
+
+        return
+
+    """
+    Extract keys from table entry in Config DB and return in a dict
+
+    Input:
+    tableKey: Config DB Primary Key, Example tableKey = "Vlan111|2a04:5555:45:6709::1/64"
+    keys: key string from YANG list, i.e. 'vlan_name ip-prefix'.
+    regex: A regex to extract keys from tableKeys, good to have it as accurate as possible.
+
+    Return:
+    KeyDict = {"vlan_name": "Vlan111", "ip-prefix": "2a04:5555:45:6709::1/64"}
+    """
+    def _extractKey(self, tableKey, keys, regex):
+
+        keyList = keys.split()
+        # get the value groups
+        value = re.match(regex, tableKey)
+        # create the keyDict
+        i = 1
+        keyDict = dict()
+        for k in keyList:
+            if value.group(i):
+                keyDict[k] = value.group(i)
+            else:
+                raise Exception("Value not found for {} in {}".format(k, tableKey))
+            i = i + 1
+
+        return keyDict
+
+    """
+    Fill the dict based on leaf as a list or dict @model yang model object
+    """
+    def _fillLeafDict(self, leafs, leafDict, isleafList=False):
+
+        if leafs is None:
+            return
+
+        # fill default values
+        def _fillSteps(leaf):
+            leaf['__isleafList'] = isleafList
+            leafDict[leaf['@name']] = leaf
+            return
+
+        if isinstance(leafs, list):
+            for leaf in leafs:
+                #print("{}:{}".format(leaf['@name'], leaf))
+                _fillSteps(leaf)
+        else:
+            #print("{}:{}".format(leaf['@name'], leaf))
+            _fillSteps(leafs)
+
+        return
+
+    """
+    create a dict to map each key under primary key with a dict yang model.
+    This is done to improve performance of mapping from values of TABLEs in
+    config DB to leaf in YANG LIST.
+    """
+    def _createLeafDict(self, model):
+
+        leafDict = dict()
+        #Iterate over leaf, choices and leaf-list.
+        self._fillLeafDict(model.get('leaf'), leafDict)
+
+        #choices, this is tricky, since leafs are under cases in tree.
+        choices = model.get('choice')
+        if choices:
+            for choice in choices:
+                cases = choice['case']
+                for case in cases:
+                    self._fillLeafDict(case.get('leaf'), leafDict)
+
+        # leaf-lists
+        self._fillLeafDict(model.get('leaf-list'), leafDict, True)
+
+        return leafDict
+
+    """
+    Convert a string from Config DB value to Yang Value based on type of the
+    key in Yang model.
+    @model : A List of Leafs in Yang model list
+    """
+    def _findYangTypedValue(self, key, value, leafDict):
+
+        # convert config DB string to yang Type
+        def _yangConvert(val):
+            # Convert everything to string
+            val = str(val)
+            # find type of this key from yang leaf
+            type = leafDict[key]['type']['@name']
+
+            if 'uint' in type:
+                vValue = int(val, 10)
+            # TODO: find type of leafref from schema node
+            elif 'leafref' in type:
+                vValue = val
+            #TODO: find type in sonic-head, as of now, all are enumeration
+            elif 'head:' in type:
+                vValue = val
+            else:
+                vValue = val
+            return vValue
+
+        # if it is a leaf-list do it for each element
+        if leafDict[key]['__isleafList']:
+            vValue = list()
+            for v in value:
+                vValue.append(_yangConvert(v))
+        else:
+            vValue = _yangConvert(value)
+
+        return vValue
+
+    """
+    Xlate a list
+    This function will xlate from a dict in config DB to a Yang JSON list
+    using yang model. Output will be go in self.xlateJson
+    """
+    def _xlateList(self, model, yang, config, table):
+
+        #create a dict to map each key under primary key with a dict yang model.
+        #This is done to improve performance of mapping from values of TABLEs in
+        #config DB to leaf in YANG LIST.
+        leafDict = self._createLeafDict(model)
+
+        # fetch regex from YANG models.
+        keyRegEx = model['ext:key-regex-configdb-to-yang']['@value']
+        # seperator `|` has special meaning in regex, so change it appropriately.
+        keyRegEx = re.sub('\|', '\\|', keyRegEx)
+        # get keys from YANG model list itself
+        listKeys = model['key']['@value']
+        self.sysLog(msg="xlateList regex:{} keyList:{}".\
+            format(keyRegEx, listKeys))
+
+        for pkey in config.keys():
+            try:
+                vKey = None
+                self.sysLog(syslog.LOG_DEBUG, "xlateList Extract pkey:{}".\
+                    format(pkey))
+                # Find and extracts key from each dict in config
+                keyDict = self._extractKey(pkey, listKeys, keyRegEx)
+                # fill rest of the values in keyDict
+                for vKey in config[pkey]:
+                    self.sysLog(syslog.LOG_DEBUG, "xlateList vkey {}".format(vKey))
+                    keyDict[vKey] = self._findYangTypedValue(vKey, \
+                                        config[pkey][vKey], leafDict)
+                yang.append(keyDict)
+                # delete pkey from config, done to match one key with one list
+                del config[pkey]
+
+            except Exception as e:
+                # log debug, because this exception may occur with multilists
+                self.sysLog(syslog.LOG_DEBUG, "xlateList Exception {}".format(e))
+                # with multilist, we continue matching other keys.
+                continue
+
+        return
+
+    """
+    Process list inside a Container.
+    This function will call xlateList based on list(s) present in Container.
+    """
+    def _xlateListInContainer(self, model, yang, configC, table):
+        clist = model
+        #print(clist['@name'])
+        yang[clist['@name']] = list()
+        self.sysLog(msg="xlateProcessListOfContainer: {}".format(clist['@name']))
+        self._xlateList(clist, yang[clist['@name']], configC, table)
+        # clean empty lists
+        if len(yang[clist['@name']]) == 0:
+            del yang[clist['@name']]
+
+        return
+
+    """
+    Process container inside a Container.
+    This function will call xlateContainer based on Container(s) present
+    in outer Container.
+    """
+    def _xlateContainerInContainer(self, model, yang, configC, table):
+        ccontainer = model
+        #print(ccontainer['@name'])
+        yang[ccontainer['@name']] = dict()
+        if not configC.get(ccontainer['@name']):
+            return
+        self.sysLog(msg="xlateProcessListOfContainer: {}".format(ccontainer['@name']))
+        self._xlateContainer(ccontainer, yang[ccontainer['@name']], \
+        configC[ccontainer['@name']], table)
+        # clean empty container
+        if len(yang[ccontainer['@name']]) == 0:
+            del yang[ccontainer['@name']]
+        # remove copy after processing
+        del configC[ccontainer['@name']]
+
+        return
+
+    """
+    Xlate a container
+    This function will xlate from a dict in config DB to a Yang JSON container
+    using yang model. Output will be stored in self.xlateJson
+    """
+    def _xlateContainer(self, model, yang, config, table):
+
+        # To Handle multiple Lists, Make a copy of config, because we delete keys
+        # from config after each match. This is done to match one pkey with one list.
+        configC = config.copy()
+
+        clist = model.get('list')
+        # If single list exists in container,
+        if clist and isinstance(clist, dict) and \
+           clist['@name'] == model['@name']+"_LIST" and bool(configC):
+                self._xlateListInContainer(clist, yang, configC, table)
+        # If multi-list exists in container,
+        elif clist and isinstance(clist, list) and bool(configC):
+            for modelList in clist:
+                self._xlateListInContainer(modelList, yang, configC, table)
+
+        # Handle container(s) in container
+        ccontainer = model.get('container')
+        # If single list exists in container,
+        if ccontainer and isinstance(ccontainer, dict) and bool(configC):
+            self._xlateContainerInContainer(ccontainer, yang, configC, table)
+        # If multi-list exists in container,
+        elif ccontainer and isinstance(ccontainer, list) and bool(configC):
+            for modelContainer in ccontainer:
+                self._xlateContainerInContainer(modelContainer, yang, configC, table)
+
+        ## Handle other leaves in container,
+        leafDict = self._createLeafDict(model)
+        for vKey in configC.keys():
+            #vkey must be a leaf\leaf-list\choice in container
+            if leafDict.get(vKey):
+                self.sysLog(syslog.LOG_DEBUG, "xlateContainer vkey {}".format(vKey))
+                yang[vKey] = self._findYangTypedValue(vKey, configC[vKey], leafDict)
+                # delete entry from copy of config
+                del configC[vKey]
+
+        # All entries in copy of config must have been parsed.
+        if len(configC):
+            self.sysLog(syslog.LOG_ERR, "Alert: Remaining keys in Config")
+            raise(Exception("All Keys are not parsed in {}\n{}".format(table, \
+                configC.keys())))
+
+        return
+
+    """
+    xlate ConfigDB json to Yang json
+    """
+    def _xlateConfigDBtoYang(self, jIn, yangJ):
+
+        # find top level container for each table, and run the xlate_container.
+        for table in jIn.keys():
+            cmap = self.confDbYangMap[table]
+            # create top level containers
+            key = cmap['module']+":"+cmap['topLevelContainer']
+            subkey = cmap['topLevelContainer']+":"+cmap['container']['@name']
+            # Add new top level container for first table in this container
+            yangJ[key] = dict() if yangJ.get(key) is None else yangJ[key]
+            yangJ[key][subkey] = dict()
+            self.sysLog(msg="xlateConfigDBtoYang {}:{}".format(key, subkey))
+            self._xlateContainer(cmap['container'], yangJ[key][subkey], \
+                                jIn[table], table)
+
+        return
+
+    """
+    Read config file and crop it as per yang models
+    """
+    def _xlateConfigDB(self, xlateFile=None):
+
+        jIn= self.jIn
+        yangJ = self.xlateJson
+        # xlation is written in self.xlateJson
+        self._xlateConfigDBtoYang(jIn, yangJ)
+
+        if xlateFile:
+            with open(xlateFile, 'w') as f:
+                dump(self.xlateJson, f, indent=4)
+
+        return
+
+    """
+    create config DB table key from entry in yang JSON
+    """
+    def _createKey(self, entry, regex):
+
+        keyDict = dict()
+        keyV = regex
+        # get the keys from regex of key extractor
+        keyList = re.findall(r'<(.*?)>', regex)
+        for key in keyList:
+            val = entry.get(key)
+            if val:
+                #print("pair: {} {}".format(key, val))
+                keyDict[key] = sval = str(val)
+                keyV = re.sub(r'<'+key+'>', sval, keyV)
+                #print("VAL: {} {}".format(regex, keyV))
+            else:
+                raise Exception("key {} not found in entry".format(key))
+        #print("kDict {}".format(keyDict))
+        return keyV, keyDict
+
+    """
+    Convert a string from Config DB value to Yang Value based on type of the
+    key in Yang model.
+    @model : A List of Leafs in Yang model list
+    """
+    def _revFindYangTypedValue(self, key, value, leafDict):
+
+        # convert yang Type to config DB string
+        def _revYangConvert(val):
+            # config DB has only strings, thank god for that :), wait not yet!!!
+            return str(val)
+
+        # if it is a leaf-list do it for each element
+        if leafDict[key]['__isleafList']:
+            vValue = list()
+            for v in value:
+                vValue.append(_revYangConvert(v))
+        else:
+            vValue = _revYangConvert(value)
+
+        return vValue
+
+    """
+    Rev xlate from <TABLE>_LIST to table in config DB
+    """
+    def _revXlateList(self, model, yang, config, table):
+
+        # fetch regex from YANG models
+        keyRegEx = model['ext:key-regex-yang-to-configdb']['@value']
+        self.sysLog(msg="revXlateList regex:{}".format(keyRegEx))
+
+        # create a dict to map each key under primary key with a dict yang model.
+        # This is done to improve performance of mapping from values of TABLEs in
+        # config DB to leaf in YANG LIST.
+        leafDict = self._createLeafDict(model)
+
+        # list with name <NAME>_LIST should be removed,
+        if "_LIST" in model['@name']:
+            for entry in yang:
+                # create key of config DB table
+                pkey, pkeydict = self._createKey(entry, keyRegEx)
+                self.sysLog(syslog.LOG_DEBUG, "revXlateList pkey:{}".format(pkey))
+                config[pkey]= dict()
+                # fill rest of the entries
+                for key in entry:
+                    if key not in pkeydict:
+                        config[pkey][key] = self._revFindYangTypedValue(key, \
+                            entry[key], leafDict)
+
+        return
+
+    """
+    Rev xlate a list inside a yang container
+    """
+    def _revXlateListInContainer(self, model, yang, config, table):
+        modelList = model
+        # Pass matching list from Yang Json if exist
+        if yang.get(modelList['@name']):
+            self.sysLog(msg="revXlateListInContainer {}".format(modelList['@name']))
+            self._revXlateList(modelList, yang[modelList['@name']], config, table)
+        return
+
+    """
+    Rev xlate a container inside a yang container
+    """
+    def _revXlateContainerInContainer(self, model, yang, config, table):
+        modelContainer = model
+        # Pass matching list from Yang Json if exist
+        if yang.get(modelContainer['@name']):
+            config[modelContainer['@name']] = dict()
+            self.sysLog(msg="revXlateContainerInContainer {}".format(modelContainer['@name']))
+            self._revXlateContainer(modelContainer, yang[modelContainer['@name']], \
+                config[modelContainer['@name']], table)
+        return
+
+    """
+    Rev xlate from yang container to table in config DB
+    """
+    def _revXlateContainer(self, model, yang, config, table):
+
+        # IF container has only one list
+        clist = model.get('list')
+        if isinstance(clist, dict):
+            self._revXlateListInContainer(clist, yang, config, table)
+        # IF container has lists
+        elif isinstance(clist, list):
+            for modelList in clist:
+                self._revXlateListInContainer(modelList, yang, config, table)
+
+        ccontainer = model.get('container')
+        # IF container has only one inner container
+        if isinstance(ccontainer, dict):
+            self._revXlateContainerInContainer(ccontainer, yang, config, table)
+        # IF container has only many inner container
+        elif isinstance(ccontainer, list):
+            for modelContainer in ccontainer:
+                self._revXlateContainerInContainer(modelContainer, yang, config, table)
+
+        ## Handle other leaves in container,
+        leafDict = self._createLeafDict(model)
+        for vKey in yang:
+            #vkey must be a leaf\leaf-list\choice in container
+            if leafDict.get(vKey):
+                self.sysLog(syslog.LOG_DEBUG, "revXlateContainer vkey {}".format(vKey))
+                config[vKey] = self._revFindYangTypedValue(vKey, yang[vKey], leafDict)
+
+        return
+
+    """
+    rev xlate ConfigDB json to Yang json
+    """
+    def _revXlateYangtoConfigDB(self, yangJ, cDbJson):
+
+        yangJ = self.xlateJson
+        cDbJson = self.revXlateJson
+
+        # find table in config DB, use name as a KEY
+        for module_top in yangJ.keys():
+            # module _top will be of from module:top
+            for container in yangJ[module_top].keys():
+                #table = container.split(':')[1]
+                table = container
+                #print("revXlate " + table)
+                cmap = self.confDbYangMap[table]
+                cDbJson[table] = dict()
+                #print(key + "--" + subkey)
+                self.sysLog(msg="revXlateYangtoConfigDB {}".format(table))
+                self._revXlateContainer(cmap['container'], yangJ[module_top][container], \
+                    cDbJson[table], table)
+
+        return
+
+    """
+    Reverse Translate tp config DB
+    """
+    def _revXlateConfigDB(self, revXlateFile=None):
+
+        yangJ = self.xlateJson
+        cDbJson = self.revXlateJson
+        # xlation is written in self.xlateJson
+        self._revXlateYangtoConfigDB(yangJ, cDbJson)
+
+        if revXlateFile:
+            with open(revXlateFile, 'w') as f:
+                dump(self.revXlateJson, f, indent=4)
+
+        return
+
+    """
+    Find a list in YANG Container
+    c = container
+    l = list name
+    return: list if found else None
+    """
+    def _findYangList(self, container, listName):
+
+        if isinstance(container['list'], dict):
+            clist = container['list']
+            if clist['@name'] == listName:
+                return clist
+
+        elif isinstance(container['list'], list):
+            clist = [l for l in container['list'] if l['@name'] == listName]
+            return clist[0]
+
+        return None
+
+    """
+    Find xpath of the PORT Leaf in PORT container/list. Xpath of Leaf is needed,
+    because only leaf can have leafrefs depend on them. (Public)
+    """
+    def findXpathPortLeaf(self, portName):
+
+        try:
+            table = "PORT"
+            xpath = self.findXpathPort(portName)
+            module, topc, container = self._getModuleTLCcontainer(table)
+            list = self._findYangList(container, table+"_LIST")
+            xpath = xpath + "/" + list['key']['@value'].split()[0]
+        except Exception as e:
+            print("find xpath of port Leaf failed")
+            raise SonicYangException("find xpath of port Leaf failed\n{}".format(str(e)))
+
+        return xpath
+
+    """
+    Find xpath of PORT. (Public)
+    """
+    def findXpathPort(self, portName):
+
+        try:
+            table = "PORT"
+            module, topc, container = self._getModuleTLCcontainer(table)
+            xpath = "/" + module + ":" + topc + "/" + table
+
+            list = self._findYangList(container, table+"_LIST")
+            xpath = self._findXpathList(xpath, list, [portName])
+        except Exception as e:
+            print("find xpath of port failed")
+            raise SonicYangException("find xpath of port failed\n{}".format(str(e)))
+
+        return xpath
+
+    """
+    Find xpath of a YANG LIST from keys,
+    xpath: xpath till list
+    list: YANG List
+    keys: list of keys in YANG LIST
+    """
+    def _findXpathList(self, xpath, list, keys):
+
+        try:
+            # add list name in xpath
+            xpath = xpath + "/" + list['@name']
+            listKeys = list['key']['@value'].split()
+            i = 0;
+            for listKey in listKeys:
+                xpath = xpath + '['+listKey+'=\''+keys[i]+'\']'
+                i = i + 1
+        except Exception as e:
+            raise e
+
+        return xpath
+
+    """
+    load_data: load Config DB, crop, xlate and create data tree from it. (Public)
+    input:    data
+    returns:  True - success   False - failed
+    """
+    def loadData(self, configdbJson):
+
+       try:
+          self.jIn = configdbJson
+          # reset xlate and tablesWithOutYang
+          self.xlateJson = dict()
+          self.tablesWithOutYang = dict()
+          # self.jIn will be cropped
+          self._cropConfigDB()
+          # xlated result will be in self.xlateJson
+          self._xlateConfigDB()
+          #print(self.xlateJson)
+          self.sysLog(msg="Try to load Data in the tree")
+          self.root = self.ctx.parse_data_mem(dumps(self.xlateJson), \
+                        ly.LYD_JSON, ly.LYD_OPT_CONFIG|ly.LYD_OPT_STRICT)
+
+       except Exception as e:
+           self.root = None
+           print("Data Loading Failed")
+           raise SonicYangException("Data Loading Failed\n{}".format(str(e)))
+
+       return True
+
+    """
+    Get data from Data tree, data tree will be assigned in self.xlateJson. (Public)
+    """
+    def getData(self):
+
+        try:
+            self.xlateJson = loads(self._print_data_mem('JSON'))
+            # reset reverse xlate
+            self.revXlateJson = dict()
+            # result will be stored self.revXlateJson
+            self._revXlateConfigDB()
+
+        except Exception as e:
+            print("Get Data Tree Failed")
+            raise SonicYangException("Get Data Tree Failed\n{}".format(str(e)))
+
+        return self.revXlateJson
+
+    """
+    Delete a node from data tree, if this is LEAF and KEY Delete the Parent.
+    (Public)
+    """
+    def deleteNode(self, xpath):
+
+        # These MACROS used only here, can we get it from Libyang Header ?
+        try:
+            LYS_LEAF = 4
+            node = self._find_data_node(xpath)
+            if node is None:
+                raise('Node {} not found'.format(xpath))
+
+            snode = node.schema()
+            # check for a leaf if it is a key. If yes delete the parent
+            if (snode.nodetype() == LYS_LEAF):
+                leaf = ly.Schema_Node_Leaf(snode)
+                if leaf.is_key():
+                    # try to delete parent
+                    nodeP = self._find_parent_data_node(xpath)
+                    xpathP = nodeP.path()
+                    if self._deleteNode(xpath=xpathP, node=nodeP) == False:
+                        raise Exception('_deleteNode failed')
+                    else:
+                        return True
+
+            # delete non key element
+            if self._deleteNode(xpath=xpath, node=node) == False:
+                raise Exception('_deleteNode failed')
+        except Exception as e:
+            raise SonicYangException("Failed to delete node {}\n{}".\
+                format( xpath, str(e)))
+
+        return True
+
+    # End of class sonic_yang

src/sonic-yang-mgmt/tests/__init__.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+"""Unit test package for sonic_yang_mgmt."""

src/sonic-yang-mgmt/tests/libyang-python-tests/config_data.json

@@ -0,0 +1,260 @@
+{
+	"test-vlan:vlan": {
+		"test-vlan:VLAN_INTERFACE": {
+			"VLAN_INTERFACE_LIST": [{
+					"vlanid": 111,
+					"ip-prefix": "2000:f500:45:6709::1/64",
+					"scope": "global",
+					"family": "IPv6"
+				},
+				{
+					"vlanid": 111,
+					"ip-prefix": "10.1.1.65/26",
+					"scope": "global",
+					"family": "IPv4"
+				},
+				{
+					"vlanid": 111,
+					"ip-prefix": "fe80::1/10",
+					"scope": "local",
+					"family": "IPv6"
+				},
+				{
+					"vlanid": 555,
+					"ip-prefix": "2000:f500:41:4e9::1/64",
+					"scope": "global",
+					"family": "IPv6"
+				},
+				{
+					"vlanid": 555,
+					"ip-prefix": "10.1.5.65/26",
+					"scope": "global",
+					"family": "IPv4"
+				},
+				{
+					"vlanid": 555,
+					"ip-prefix": "fe80::1/10",
+					"scope": "local",
+					"family": "IPv6"
+				}
+			]
+		},
+
+		"test-vlan:VLAN": {
+			"VLAN_LIST": [{
+					"vlanid": 111,
+					"description": "server_vlan",
+					"dhcp_servers": [
+						"10.1.7.116"
+					],
+					"mtu": "9216",
+					"admin_status": "up"
+				},
+				{
+					"vlanid": 555,
+					"description": "ipmi_vlan",
+					"dhcp_servers": [
+						"10.1.7.116"
+					],
+					"mtu": "9216",
+					"admin_status": "up"
+				}
+			]
+		},
+
+		"test-vlan:VLAN_MEMBER": {
+			"VLAN_MEMBER_LIST": [{
+					"vlanid": 111,
+					"port": "Ethernet0",
+					"tagging_mode": "tagged"
+				},
+				{
+					"vlanid": 111,
+					"port": "Ethernet1",
+					"tagging_mode": "tagged"
+				},
+				{
+					"vlanid": 111,
+					"port": "Ethernet2",
+					"tagging_mode": "tagged"
+				},
+				{
+					"vlanid": 111,
+					"port": "Ethernet3",
+					"tagging_mode": "tagged"
+				},
+				{
+					"vlanid": 111,
+					"port": "Ethernet4",
+					"tagging_mode": "tagged"
+				},
+				{
+					"vlanid": 111,
+					"port": "Ethernet5",
+					"tagging_mode": "tagged"
+				},
+				{
+					"vlanid": 111,
+					"port": "Ethernet6",
+					"tagging_mode": "tagged"
+				}
+			]
+		}
+	},
+	"test-port:port": {
+		"test-port:PORT": {
+			"PORT_LIST": [{
+					"port_name": "Ethernet0",
+					"alias": "eth0",
+					"description": "Ethernet0",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet1",
+					"alias": "eth1",
+					"description": "Ethernet1",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet2",
+					"alias": "eth2",
+					"description": "Ethernet2",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet3",
+					"alias": "eth2",
+					"description": "Ethernet3",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet4",
+					"alias": "eth4",
+					"description": "Ethernet4",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet5",
+					"alias": "eth5",
+					"description": "Ethernet5",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet6",
+					"alias": "eth6",
+					"description": "Ethernet6",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet7",
+					"alias": "eth7",
+					"description": "Ethernet7",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet8",
+					"alias": "eth8",
+					"description": "Ethernet8",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet9",
+					"alias": "eth9",
+					"description": "Ethernet9",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				}
+			]
+		}
+	},
+
+	"test-acl:acl": {
+		"test-acl:ACL_RULE": {
+			"ACL_RULE_LIST": [{
+					"ACL_TABLE_NAME": "PACL-V4",
+					"RULE_NAME": "Rule_20",
+					"PACKET_ACTION": "FORWARD",
+					"DST_IP": "10.1.72.0/26",
+					"SRC_IP": "10.1.0.0/15",
+					"PRIORITY": "999980",
+					"IP_TYPE": "IPV4ANY"
+				},
+				{
+					"ACL_TABLE_NAME": "PACL-V4",
+					"RULE_NAME": "Rule_40",
+					"PACKET_ACTION": "FORWARD",
+					"DST_IP": "10.1.72.64/26",
+					"SRC_IP": "10.1.0.0/15",
+					"PRIORITY": "999960",
+					"IP_TYPE": "IPV4ANY",
+					"INNER_ETHER_TYPE": "0x88CC"
+				},
+				{
+					"ACL_TABLE_NAME": "PACL-V6",
+					"RULE_NAME": "Rule_20",
+					"PACKET_ACTION": "FORWARD",
+					"IP_TYPE": "IP",
+					"SRC_IPV6": "2000:f500:41::/48",
+					"PRIORITY": "999980",
+					"DST_IPV6": "2000:f500:43:320::/64",
+					"L4_SRC_PORT_RANGE": "653-1053"
+				}
+			]
+		},
+
+		"test-acl:ACL_TABLE": {
+			"ACL_TABLE_LIST": [{
+					"ACL_TABLE_NAME": "PACL-V6",
+					"policy_desc": "Filter IPv6",
+					"type": "L3V6",
+					"stage": "EGRESS",
+					"ports": ["Ethernet7", "Ethernet9", "Ethernet8"]
+				},
+				{
+					"ACL_TABLE_NAME": "PACL-V4",
+					"policy_desc": "Filter IPv6",
+					"type": "L3",
+					"stage": "INGRESS",
+					"ports": ["Ethernet2", "Ethernet0", "Ethernet1"]
+				}
+			]
+		}
+	},
+
+	"test-interface:interface": {
+		"test-interface:INTERFACE": {
+			"INTERFACE_LIST": [{
+					"interface": "Ethernet8",
+					"ip-prefix": "10.1.1.65/26",
+					"scope": "global",
+					"family": "IPv4"
+				},
+				{
+					"interface": "Ethernet8",
+					"ip-prefix": "2000:f500:40:a749::2/126",
+					"scope": "global",
+					"family": "IPv6"
+				}
+			]
+		}
+	}
+}

src/sonic-yang-mgmt/tests/libyang-python-tests/config_data_merge.json

@@ -0,0 +1,154 @@
+{
+	"test-vlan:vlan": {
+		"test-vlan:VLAN_INTERFACE": {
+			"VLAN_INTERFACE_LIST": [{
+					"vlanid": 111,
+					"ip-prefix": "2000:f500:45:6709::1/64",
+					"scope": "global",
+					"family": "IPv6"
+				},
+				{
+					"vlanid": 111,
+					"ip-prefix": "10.1.1.64/26",
+					"scope": "global",
+					"family": "IPv4"
+				},
+				{
+					"vlanid": 200,
+					"ip-prefix": "2000:f500:45:6708::1/64",
+					"scope": "global",
+					"family": "IPv6"
+				},
+				{
+					"vlanid": 200,
+					"ip-prefix": "2000:f500:45:6709::1/64",
+					"scope": "global",
+					"family": "IPv6"
+				}
+			]
+		},
+
+		"test-vlan:VLAN": {
+			"VLAN_LIST": [{
+					"vlanid": 200,
+					"description": "server_vlan",
+					"dhcp_servers": [
+						"10.1.72.116"
+					],
+					"mtu": "9216",
+					"admin_status": "up"
+				},
+				{
+					"vlanid": 111,
+					"description": "server_vlan",
+					"dhcp_servers": [
+						"10.1.72.116"
+					],
+					"mtu": "9216",
+					"admin_status": "up"
+				}
+			]
+		},
+
+		"test-vlan:VLAN_MEMBER": {
+			"VLAN_MEMBER_LIST": [{
+				"vlanid": 200,
+				"port": "Ethernet0",
+				"tagging_mode": "tagged"
+			}]
+		}
+	},
+	"test-port:port": {
+		"test-port:PORT": {
+			"PORT_LIST": [{
+					"port_name": "Ethernet0",
+					"alias": "eth0",
+					"description": "Ethernet0",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet1",
+					"alias": "eth1",
+					"description": "Ethernet1",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet2",
+					"alias": "eth2",
+					"description": "Ethernet2",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet3",
+					"alias": "eth2",
+					"description": "Ethernet3",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet4",
+					"alias": "eth4",
+					"description": "Ethernet4",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet5",
+					"alias": "eth5",
+					"description": "Ethernet5",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet6",
+					"alias": "eth6",
+					"description": "Ethernet6",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet7",
+					"alias": "eth7",
+					"description": "Ethernet7",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet8",
+					"alias": "eth8",
+					"description": "Ethernet8",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet9",
+					"alias": "eth9",
+					"description": "Ethernet9",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				},
+				{
+					"port_name": "Ethernet10",
+					"alias": "eth10",
+					"description": "Ethernet10",
+					"speed": 25000,
+					"mtu": 9000,
+					"admin_status": "up"
+				}
+			]
+		}
+	}
+}

src/sonic-yang-mgmt/tests/libyang-python-tests/sample-yang-models/test-acl.yang

@@ -0,0 +1,268 @@
+module test-acl {
+
+	yang-version 1.1;
+
+	namespace "http://github.com/Azure/acl";
+	prefix acl;
+
+	import ietf-yang-types {
+		prefix yang;
+	}
+
+	import ietf-inet-types {
+		prefix inet;
+	}
+
+	import test-head {
+		prefix head;
+		revision-date 2019-07-01;
+	}
+
+	import test-port {
+		prefix port;
+		revision-date 2019-07-01;
+	}
+
+	import test-portchannel {
+		prefix lag;
+		revision-date 2019-07-01;
+	}
+
+	revision 2019-07-01 {
+		description "First Revision";
+	}
+
+	container acl {
+
+		container ACL_RULE {
+
+			description "ACL_RULE part of config_db.json";
+
+			list ACL_RULE_LIST {
+
+				key "ACL_TABLE_NAME RULE_NAME";
+
+				leaf ACL_TABLE_NAME {
+					type leafref {
+						path "/acl:acl/acl:ACL_TABLE/acl:ACL_TABLE_LIST/acl:ACL_TABLE_NAME";
+					}
+				}
+
+				leaf RULE_NAME {
+					type string {
+						length 1..255;
+					}
+				}
+
+				leaf PACKET_ACTION {
+					type head:packet_action;
+				}
+
+				leaf IP_TYPE {
+					type head:ip_type;
+				}
+
+				leaf PRIORITY {
+					type uint32 {
+						range 0..999999;
+					}
+				}
+
+				choice ip_prefix {
+
+					case ip4_prefix {
+						when "boolean(IP_TYPE[.='ANY' or .='IP' or .='IPV4' or .='IPV4ANY' or .='ARP'])";
+						leaf SRC_IP {
+							type inet:ipv4-prefix;
+						}
+
+						leaf DST_IP {
+							type inet:ipv4-prefix;
+						}
+					}
+
+					case ip6_prefix {
+						when "boolean(IP_TYPE[.='ANY' or .='IP' or .='IPV6' or .='IPV6ANY'])";
+						leaf SRC_IPV6 {
+							type inet:ipv6-prefix;
+						}
+
+						leaf DST_IPV6 {
+							type inet:ipv6-prefix;
+						}
+					}
+				}
+
+				leaf-list IN_PORTS {
+					/* Values in leaf list are UNIQUE */
+					type uint16;
+				}
+
+				leaf-list OUT_PORTS {
+					/* Values in leaf list are UNIQUE */
+					type uint16;
+				}
+
+				choice src_port {
+					case l4_src_port {
+						leaf L4_SRC_PORT {
+							type uint16;
+						}
+					}
+
+					case l4_src_port_range {
+						leaf L4_SRC_PORT_RANGE {
+							type string {
+								pattern '([0-9]{1,4}|[0-5][0-9]{4}|[6][0-4][0-9]{3}|[6][5][0-2][0-9]{2}|[6][5][3][0-5]{2}|[6][5][3][6][0-5])-([0-9]{1,4}|[0-5][0-9]{4}|[6][0-4][0-9]{3}|[6][5][0-2][0-9]{2}|[6][5][3][0-5]{2}|[6][5][3][6][0-5])';
+							}
+						}
+					}
+				}
+
+				choice dst_port {
+					case l4_dst_port {
+						leaf L4_DST_PORT {
+							type uint16;
+						}
+					}
+
+					case l4_dst_port_range {
+						leaf L4_DST_PORT_RANGE {
+							type string {
+								pattern '([0-9]{1,4}|[0-5][0-9]{4}|[6][0-4][0-9]{3}|[6][5][0-2][0-9]{2}|[6][5][3][0-5]{2}|[6][5][3][6][0-5])-([0-9]{1,4}|[0-5][0-9]{4}|[6][0-4][0-9]{3}|[6][5][0-2][0-9]{2}|[6][5][3][0-5]{2}|[6][5][3][6][0-5])';
+							}
+						}
+					}
+				}
+
+				leaf ETHER_TYPE {
+					type string {
+						pattern "(0x88CC|0x8100|0x8915|0x0806|0x0800|0x86DD|0x8847)";
+					}
+				}
+
+				leaf IP_PROTOCOL {
+					type uint8 {
+						range 1..143;
+					}
+				}
+
+				leaf TCP_FLAGS {
+					type string {
+						pattern '0[x][0-9a-fA-F]{1,2}|0[X][0-9a-fA-F]{1,2}';
+					}
+				}
+
+				leaf DSCP {
+					type uint8;
+				}
+
+				leaf TC {
+					type uint8;
+				}
+
+				choice icmp {
+
+					case icmp4 {
+						when "boolean(IP_TYPE[.='ANY' or .='IP' or .='IPV4' or .='IPV4ANY' or .='ARP'])";
+						leaf ICMP_TYPE {
+							type uint8 {
+								range 1..44;
+							}
+						}
+
+						leaf ICMP_CODE {
+							type uint8 {
+								range 1..16;
+							}
+						}
+					}
+
+					case icmp6 {
+						when "boolean(IP_TYPE[.='ANY' or .='IP' or .='IPV6' or .='IPV6ANY'])";
+						leaf ICMPV6_TYPE {
+							type uint8 {
+								range 1..44;
+							}
+						}
+
+						leaf ICMPV6_CODE {
+							type uint8 {
+								range 1..16;
+							}
+						}
+					}
+				}
+
+				leaf INNER_ETHER_TYPE {
+					type string {
+						pattern "(0x88CC|0x8100|0x8915|0x0806|0x0800|0x86DD|0x8847)";
+					}
+				}
+
+				leaf INNER_IP_PROTOCOL {
+					type uint8 {
+						range 1..143;
+					}
+				}
+
+				leaf INNER_L4_SRC_PORT {
+					type uint16;
+				}
+
+				leaf INNER_L4_DST_PORT {
+					type uint16;
+				}
+			}
+			/* end of ACL_RULE_LIST */
+		}
+		/* end of container ACL_RULE */
+
+		container ACL_TABLE {
+
+			description "ACL_TABLE part of config_db.json";
+
+			list ACL_TABLE_LIST {
+
+				key "ACL_TABLE_NAME";
+
+				leaf ACL_TABLE_NAME {
+					type string;
+				}
+
+				leaf policy_desc {
+					type string {
+						length 1..255;
+					}
+				}
+
+				leaf type {
+					type head:acl_table_type;
+				}
+
+				leaf stage {
+					type enumeration {
+						enum INGRESS;
+						enum EGRESS;
+					}
+				}
+
+				leaf-list ports {
+                    /* union of leafref is allowed in YANG 1.1 */
+					type union {
+						type leafref {
+							path /port:port/port:PORT/port:PORT_LIST/port:port_name;
+						}
+						type leafref {
+							path /lag:portchannel/lag:PORTCHANNEL/lag:PORTCHANNEL_LIST/lag:portchannel_name;
+						}
+					}
+				}
+			}
+			/* end of ACL_TABLE_LIST */
+		}
+        /* end of container ACL_TABLE */
+	}
+    /* end of container acl */
+}
+/* end of module acl */

src/sonic-yang-mgmt/tests/libyang-python-tests/sample-yang-models/test-head.yang

@@ -0,0 +1,66 @@
+module test-head {
+
+    namespace "http://head";
+    prefix head;
+
+    revision 2019-07-01 {
+        description "First Revision";
+    }
+
+    typedef ip-family {
+        type enumeration {
+            enum IPv4;
+            enum IPv6;
+        }
+    }
+
+    typedef admin_status {
+        type enumeration {
+            enum up;
+            enum down;
+        }
+    }
+
+    typedef packet_action{
+        type enumeration {
+            enum DROP;
+            enum FORWARD;
+            enum REDIRECT;
+        }
+    }
+
+    typedef ip_type {
+        type enumeration {
+            enum ANY;
+            enum IP;
+            enum NON_IP;
+            enum IPV4;
+            enum IPV6;
+            enum IPV4ANY;
+            enum NON_IPv4;
+            enum IPV6ANY;
+            enum NON_IPv6;
+            enum ARP;
+        }
+    }
+
+    typedef acl_table_type {
+        type enumeration {
+            enum L2;
+            enum L3;
+            enum L3V6;
+            enum MIRROR;
+            enum MIRRORV6;
+            enum MIRROR_DSCP;
+            enum CTRLPLANE;
+        }
+    }
+
+    typedef vlan_tagging_mode {
+        type enumeration {
+            enum tagged;
+            enum untagged;
+            enum priority_tagged;
+        }
+    }
+}

src/sonic-yang-mgmt/tests/libyang-python-tests/sample-yang-models/test-interface.yang

@@ -0,0 +1,72 @@
+module test-interface {
+
+	namespace "http://github.com/Azure/interface";
+	prefix intf;
+
+	import ietf-yang-types {
+		prefix yang;
+	}
+
+	import ietf-inet-types {
+		prefix inet;
+	}
+
+	import test-head {
+		prefix head;
+		revision-date 2019-07-01;
+	}
+
+	import test-port {
+		prefix port;
+		revision-date 2019-07-01;
+	}
+
+	revision 2019-07-01 {
+		description "First Revision";
+	}
+
+	container interface {
+		container INTERFACE {
+
+			description "INTERFACE part of config_db.json";
+
+			list INTERFACE_LIST {
+
+				key "interface ip-prefix";
+
+				leaf interface {
+					type leafref {
+						path /port:port/port:PORT/port:PORT_LIST/port:port_name;
+					}
+				}
+
+				leaf ip-prefix {
+					type inet:ip-prefix;
+				}
+
+				leaf scope {
+					type enumeration {
+						enum global;
+						enum local;
+					}
+				}
+
+				leaf family {
+
+					/* family leaf needed for backward compatibility
+					   Both ip4 and ip6 address are string in IETF RFC 6021,
+					   so must statement can check based on : or ., family
+					   should be IPv4 or IPv6 according.
+					 */
+
+					must "(contains(../ip-prefix, ':') and current()='IPv6') or
+						(contains(../ip-prefix, '.') and current()='IPv4')";
+					type head:ip-family;
+				}
+			}
+			/* end of INTERFACE_LIST */
+
+		}
+		/* end of INTERFACE container */
+	}
+}

src/sonic-yang-mgmt/tests/libyang-python-tests/sample-yang-models/test-port.yang

@@ -0,0 +1,78 @@
+module test-port{
+
+	namespace "http://github.com/Azure/port";
+	prefix port;
+
+	import ietf-yang-types {
+		prefix yang;
+	}
+
+	import ietf-inet-types {
+		prefix inet;
+	}
+
+	import test-head {
+		prefix head;
+		revision-date 2019-07-01;
+	}
+
+	revision 2019-07-01 {
+		description "First Revision";
+	}
+
+	container port{
+		container PORT {
+
+			description "PORT part of config_db.json";
+
+			list PORT_LIST {
+
+				key "port_name";
+
+				leaf port_name {
+					type string {
+						length 1..128;
+					}
+				}
+
+				leaf alias {
+					type string {
+						length 1..128;
+					}
+				}
+
+				leaf lanes {
+					type string {
+						length 1..128;
+					}
+				}
+
+				leaf description {
+					type string {
+						length 1..255;
+					}
+				}
+
+				leaf speed {
+					type uint32 {
+						range 1..100000;
+					}
+				}
+
+				leaf mtu {
+					type uint16 {
+						range 1..9216;
+					}
+				}
+
+				leaf admin_status {
+					mandatory true;
+					type head:admin_status;
+				}
+			} /* end of list PORT_LIST */
+
+		} /* end of container PORT */
+
+	} /* end of container port */
+
+} /* end of module port */

src/sonic-yang-mgmt/tests/libyang-python-tests/sample-yang-models/test-portchannel.yang

@@ -0,0 +1,79 @@
+module test-portchannel {
+
+	namespace "http://github.com/Azure/portchannel";
+	prefix lag;
+
+	import ietf-yang-types {
+		prefix yang;
+	}
+
+	import ietf-inet-types {
+		prefix inet;
+	}
+
+	import test-head {
+		prefix head;
+		revision-date 2019-07-01;
+	}
+
+	import test-port {
+		prefix port;
+		revision-date 2019-07-01;
+	}
+
+	revision 2019-07-01 {
+		description "First Revision";
+	}
+
+	container portchannel {
+		container PORTCHANNEL {
+
+			description "PORTCHANNEL part of config_db.json";
+
+			list PORTCHANNEL_LIST {
+
+				key "portchannel_name";
+
+				leaf portchannel_name {
+					type string {
+						length 1..128;
+						pattern 'PortChannel[0-9]{1,4}';
+					}
+				}
+
+				leaf-list members {
+					/* leaf-list members are unique by default */
+					type leafref {
+						path /port:port/port:PORT/port:PORT_LIST/port:port_name;
+					}
+				}
+
+				leaf min_links {
+					type uint8 {
+						range 1..128;
+					}
+				}
+
+				leaf description {
+					type string {
+						length 1..255;
+					}
+				}
+
+				leaf mtu {
+					type uint16 {
+						range 1..9216;
+					}
+				}
+
+				leaf admin_status {
+					mandatory true;
+					type head:admin_status;
+				}
+			} /* end of list PORTCHANNEL_LIST */
+
+		} /* end of container PORTCHANNEL */
+
+	} /* end of container portchannel */
+
+} /* end of module port */

src/sonic-yang-mgmt/tests/libyang-python-tests/sample-yang-models/test-vlan.yang

@@ -0,0 +1,144 @@
+module test-vlan {
+
+	namespace "http://github.com/Azure/vlan";
+	prefix vlan;
+
+	import ietf-yang-types {
+		prefix yang;
+	}
+
+	import ietf-inet-types {
+		prefix inet;
+	}
+
+	import test-head {
+		prefix head;
+		revision-date 2019-07-01;
+	}
+
+	import test-port {
+		prefix port;
+		revision-date 2019-07-01;
+	}
+
+	revision 2019-07-01 {
+		description "First Revision";
+	}
+
+	container vlan {
+		container VLAN_INTERFACE {
+
+			description "VLAN_INTERFACE part of config_db.json";
+
+			list VLAN_INTERFACE_LIST {
+
+				key "vlanid ip-prefix";
+
+				leaf vlanid {
+					type leafref {
+						path ../../../VLAN/VLAN_LIST/vlanid;
+					}
+				}
+
+				leaf ip-prefix {
+					mandatory true;
+					type inet:ip-prefix;
+				}
+
+				leaf scope {
+					type enumeration {
+						enum global;
+						enum local;
+					}
+				}
+
+				leaf family {
+
+					/* family leaf needed for backward compatibility
+					   Both ip4 and ip6 address are string in IETF RFC 6021,
+					   so must statement can check based on : or ., family
+					   should be IPv4 or IPv6 according.
+					 */
+
+					must "(contains(../ip-prefix, ':') and current()='IPv6') or
+						(contains(../ip-prefix, '.') and current()='IPv4')";
+					type head:ip-family;
+				}
+			}
+			/* end of VLAN_INTERFACE_LIST */
+		}
+		/* end of VLAN_INTERFACE container */
+
+		container VLAN {
+
+			description "VLAN part of config_db.json";
+
+			list VLAN_LIST {
+
+				key "vlanid";
+
+				leaf vlanid {
+					type uint16 {
+						range 1..4094;
+					}
+				}
+
+				leaf description {
+					type string {
+						length 1..255;
+					}
+				}
+
+				leaf-list dhcp_servers {
+					type inet:ip-address;
+				}
+
+				leaf mtu {
+					type uint16 {
+						range 1..9216;
+					}
+				}
+
+				leaf admin_status {
+					mandatory true;
+					type head:admin_status;
+				}
+			}
+			/* end of VLAN_LIST */
+		}
+		/* end of container VLAN */
+
+		container VLAN_MEMBER {
+
+			description "VLAN_MEMBER part of config_db.json";
+
+			list VLAN_MEMBER_LIST {
+
+				key "vlanid port";
+
+				leaf vlanid {
+					type leafref {
+						path ../../../VLAN/VLAN_LIST/vlanid;
+					}
+				}
+
+				leaf port {
+					/* key elements are mandatory by default */
+					mandatory true;
+					type leafref {
+						path /port:port/port:PORT/port:PORT_LIST/port:port_name;
+					}
+				}
+
+				leaf tagging_mode {
+					mandatory true;
+					type head:vlan_tagging_mode;
+				}
+			}
+            /* end of list VLAN_MEMBER_LIST */
+		}
+        /* end of container VLAN_MEMBER */
+	}
+    /* end of container vlan */
+}
+/* end of module vlan */

src/sonic-yang-mgmt/tests/libyang-python-tests/sample_config_db.json

@@ -0,0 +1,648 @@
+{
+	"VLAN_INTERFACE": {
+		"Vlan111|2a04:5555:45:6709::1/64": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Vlan111|10.222.10.65/26": {
+			"scope": "global",
+			"family": "IPv4"
+		},
+		"Vlan111|fe80::1/10": {
+			"scope": "local",
+			"family": "IPv6"
+		},
+		"Vlan777|2a04:5555:41:4e9::1/64": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Vlan777|10.111.58.65/26": {
+			"scope": "global",
+			"family": "IPv4"
+		},
+		"Vlan777|fe80::1/10": {
+			"scope": "local",
+			"family": "IPv6"
+		}
+	},
+	"ACL_RULE": {
+		"V4-ACL-TABLE|DEFAULT_DENY": {
+			"PACKET_ACTION": "DROP",
+			"IP_TYPE": "IPv4ANY",
+			"PRIORITY": "0"
+		},
+		"V4-ACL-TABLE|Rule_20": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.222.72.0/26",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777780",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_40": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.222.72.64/26",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777760",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_60": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.222.80.0/26",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777740",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_80": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.222.80.64/26",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777720",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_111": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.152.17.52/32",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777700",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_120": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.252.208.41/32",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777880",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_140": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.148.128.245/32",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777860",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_160": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.222.1.245/32",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777840",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_180": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "10.252.222.21/32",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "777820",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_9000": {
+			"PACKET_ACTION": "DROP",
+			"DST_IP": "0.0.0.0/0",
+			"SRC_IP": "10.222.0.0/15",
+			"PRIORITY": "991110",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V4-ACL-TABLE|Rule_11100": {
+			"PACKET_ACTION": "FORWARD",
+			"DST_IP": "0.0.0.0/0",
+			"SRC_IP": "0.0.0.0/0",
+			"PRIORITY": "990000",
+			"IP_TYPE": "IPv4ANY"
+		},
+		"V6-ACL-TBLE|DEFAULT_DENY": {
+			"PACKET_ACTION": "DROP",
+			"IP_TYPE": "IPv6ANY",
+			"PRIORITY": "0"
+		},
+		"V6-ACL-TBLE|Rule_20": {
+			"PACKET_ACTION": "FORWARD",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "2a04:5555:41::/48",
+			"PRIORITY": "777780",
+			"DST_IPV6": "2a04:5555:43:320::/64"
+		},
+		"V6-ACL-TBLE|Rule_40": {
+			"PACKET_ACTION": "FORWARD",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "2a04:5555:41::/48",
+			"PRIORITY": "777760",
+			"DST_IPV6": "2a04:5555:43:321::/64"
+		},
+		"V6-ACL-TBLE|Rule_60": {
+			"PACKET_ACTION": "FORWARD",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "2a04:5555:41::/48",
+			"PRIORITY": "777740",
+			"DST_IPV6": "2a04:5555:43:340::/64"
+		},
+		"V6-ACL-TBLE|Rule_80": {
+			"PACKET_ACTION": "FORWARD",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "2a04:5555:41::/48",
+			"PRIORITY": "777720",
+			"DST_IPV6": "2a04:5555:43:341::/64"
+		},
+		"V6-ACL-TBLE|Rule_111": {
+			"PACKET_ACTION": "FORWARD",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "2a04:5555:41::/48",
+			"PRIORITY": "777700",
+			"DST_IPV6": "2a04:5555:32:12::/64"
+		},
+		"V6-ACL-TBLE|Rule_9000": {
+			"PACKET_ACTION": "DROP",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "2a04:5555:41::/48",
+			"PRIORITY": "991110",
+			"DST_IPV6": "::/0"
+		},
+		"V6-ACL-TBLE|Rule_11100": {
+			"PACKET_ACTION": "FORWARD",
+			"IP_TYPE": "IPv6ANY",
+			"SRC_IPV6": "::/0",
+			"PRIORITY": "990000",
+			"DST_IPV6": "::/0"
+		}
+	},
+	"DEVICE_METADATA": {
+		"localhost": {
+			"mg_type": "ToR",
+			"mac": "00:11:22:33:dd:5a",
+			"hostname": "asw.dc",
+			"bgp_asn": "64850",
+			"hwsku": "Stone"
+		}
+	},
+	"VLAN": {
+		"Vlan111": {
+			"description": "svlan",
+			"dhcp_servers": [
+				"10.222.72.116"
+			],
+			"vlanid": "111",
+			"mtu": "9216",
+			"admin_status": "up",
+			"members": [
+				"Ethernet8",
+				"Ethernet3",
+				"Ethernet0",
+				"Ethernet1",
+				"Ethernet6",
+				"Ethernet4",
+				"Ethernet5",
+				"Ethernet9",
+				"Ethernet2",
+				"Ethernet7",
+				"Ethernet32",
+				"Ethernet30",
+				"Ethernet31",
+				"Ethernet36",
+				"Ethernet34",
+				"Ethernet33",
+				"Ethernet35",
+				"Ethernet29",
+				"Ethernet21",
+				"Ethernet20",
+				"Ethernet23",
+				"Ethernet22",
+				"Ethernet27",
+				"Ethernet26",
+				"Ethernet18",
+				"Ethernet19",
+				"Ethernet14",
+				"Ethernet15",
+				"Ethernet16",
+				"Ethernet17",
+				"Ethernet10",
+				"Ethernet11",
+				"Ethernet12",
+				"Ethernet13",
+				"Ethernet28"
+			]
+		},
+		"Vlan777": {
+			"description": "pvlan",
+			"dhcp_servers": [
+				"10.222.72.116"
+			],
+			"vlanid": "777",
+			"mtu": "9216",
+			"admin_status": "up",
+			"members": [
+				"Ethernet9",
+				"Ethernet2",
+				"Ethernet8",
+				"Ethernet27",
+				"Ethernet14",
+				"Ethernet35"
+			]
+		}
+	},
+	"DEVICE_NEIGHBOR": {
+		"Ethernet112": {
+			"name": "dccsw01.nw",
+			"port": "Eth18"
+		},
+		"Ethernet114": {
+			"name": "dccsw02.nw",
+			"port": "Eth18"
+		},
+		"Ethernet116": {
+			"name": "dccsw03.nw",
+			"port": "Eth18"
+		},
+		"Ethernet118": {
+			"name": "dccsw04.nw",
+			"port": "Eth18"
+		}
+	},
+	"PORT": {
+		"Ethernet0": {
+			"alias": "Eth1/1",
+			"lanes": "65",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet1": {
+			"alias": "Eth1/2",
+			"lanes": "66",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet2": {
+			"alias": "Eth1/3",
+			"lanes": "67",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet3": {
+			"alias": "Eth1/4",
+			"lanes": "68",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet4": {
+			"alias": "Eth2/1",
+			"lanes": "69",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet5": {
+			"alias": "Eth2/2",
+			"lanes": "70",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet6": {
+			"alias": "Eth2/3",
+			"lanes": "71",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet7": {
+			"alias": "Eth2/4",
+			"lanes": "72",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet8": {
+			"alias": "Eth3/1",
+			"lanes": "73",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet9": {
+			"alias": "Eth3/2",
+			"lanes": "74",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet10": {
+			"alias": "Eth3/3",
+			"lanes": "75",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet11": {
+			"alias": "Eth3/4",
+			"lanes": "76",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet12": {
+			"alias": "Eth4/1",
+			"lanes": "77",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet13": {
+			"alias": "Eth4/2",
+			"lanes": "78",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet14": {
+			"alias": "Eth4/3",
+			"lanes": "79",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet15": {
+			"alias": "Eth4/4",
+			"lanes": "80",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet16": {
+			"alias": "Eth5/1",
+			"lanes": "33",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet17": {
+			"alias": "Eth5/2",
+			"lanes": "34",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet18": {
+			"alias": "Eth5/3",
+			"lanes": "35",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet19": {
+			"alias": "Eth5/4",
+			"lanes": "36",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet20": {
+			"alias": "Eth6/1",
+			"lanes": "37",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet21": {
+			"alias": "Eth6/2",
+			"lanes": "38",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet22": {
+			"alias": "Eth6/3",
+			"lanes": "39",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet23": {
+			"alias": "Eth6/4",
+			"lanes": "40",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet24": {
+			"alias": "Eth7/1",
+			"lanes": "41",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet25": {
+			"alias": "Eth7/2",
+			"lanes": "42",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet26": {
+			"alias": "Eth7/3",
+			"lanes": "43",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet27": {
+			"alias": "Eth7/4",
+			"lanes": "44",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet28": {
+			"alias": "Eth8/1",
+			"lanes": "45",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet29": {
+			"alias": "Eth8/2",
+			"lanes": "46",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet30": {
+			"alias": "Eth8/3",
+			"lanes": "47",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet31": {
+			"alias": "Eth8/4",
+			"lanes": "48",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet32": {
+			"alias": "Eth9/1",
+			"lanes": "49",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet33": {
+			"alias": "Eth9/2",
+			"lanes": "50",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet34": {
+			"alias": "Eth9/3",
+			"lanes": "51",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet35": {
+			"alias": "Eth9/4",
+			"lanes": "52",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet36": {
+			"alias": "Eth10/1",
+			"lanes": "53",
+			"description": "",
+			"speed": "11100",
+			"admin_status": "up"
+		},
+		"Ethernet112": {
+			"alias": "Eth29/1",
+			"lanes": "113,114",
+			"description": "50G|dccsw01.nw|Eth18",
+			"fec": "fc",
+			"admin_status": "up"
+		}
+	},
+	"ACL_TABLE": {
+		"V4-ACL-TABLE": {
+			"type": "L3",
+			"policy_desc": "V4-ACL-TABLE",
+			"ports": [
+				"Ethernet26",
+				"Ethernet27",
+				"Ethernet24"
+			]
+		},
+		"V6-ACL-TBLE": {
+			"type": "L3V6",
+			"policy_desc": "V6-ACL-TBLE",
+			"ports": [
+				"Ethernet14",
+				"Ethernet15",
+				"Ethernet23",
+				"Ethernet30",
+				"Ethernet31",
+				"Ethernet18",
+				"Ethernet19",
+				"Ethernet25",
+				"Ethernet24"
+			]
+		}
+	},
+	"INTERFACE": {
+		"Ethernet112|2a04:5555:40:a709::2/126": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Ethernet112|10.184.228.211/31": {
+			"scope": "global",
+			"family": "IPv4"
+		},
+		"Ethernet14|2a04:5555:40:a749::2/126": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Ethernet14|10.184.229.211/31": {
+			"scope": "global",
+			"family": "IPv4"
+		},
+		"Ethernet16|2a04:5555:40:a789::2/126": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Ethernet16|10.184.230.211/31": {
+			"scope": "global",
+			"family": "IPv4"
+		},
+		"Ethernet18|2a04:5555:40:a7c9::2/126": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Ethernet18|10.184.231.211/31": {
+			"scope": "global",
+			"family": "IPv4"
+		}
+	},
+	"VLAN_MEMBER": {
+		"Vlan111|Ethernet0": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet1": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet2": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet3": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet4": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet5": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet6": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet29": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet30": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet31": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet32": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet33": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet34": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet35": {
+			"tagging_mode": "untagged"
+		},
+		"Vlan111|Ethernet36": {
+			"tagging_mode": "untagged"
+		}
+	},
+	"LOOPBACK_INTERFACE": {
+		"Loopback0|2a04:5555:40:4::4e9/128": {
+			"scope": "global",
+			"family": "IPv6"
+		},
+		"Loopback0|10.184.8.233/32": {
+			"scope": "global",
+			"family": "IPv4"
+		}
+	},
+	"CRM": {
+		"Config": {
+			"polling_interval": "0"
+		}
+	}
+}

src/sonic-yang-mgmt/tests/libyang-python-tests/test_SonicYang.json

@@ -0,0 +1,144 @@
+{
+  "yang_dir":"./tests/libyang-python-tests/sample-yang-models/",
+  "data_file":"./tests/libyang-python-tests/config_data.json",
+  "data_merge_file":"./tests/libyang-python-tests/config_data_merge.json",
+  "modules":[
+    {"file":"test-head.yang", "module":"test-head"},
+    {"file":"test-port.yang", "module":"test-port"},
+    {"file":"test-acl.yang",  "module":"test-acl"},
+    {"file":"test-interface.yang", "module":"test-interface"},
+    {"file":"test-portchannel.yang", "module":"test-portchannel"},
+    {"file":"test-vlan.yang", "module":"test-vlan"}
+    ],
+
+  "merged_nodes":[
+    {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet10']/speed",  "value":"25000"},
+    {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='200'][ip-prefix='2000:f500:45:6708::/64']/family",
+           "value":"IPv6"}
+  ],
+
+  "new_nodes":[
+    {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet12']/alias", "value":"Ethernet10_alias"},
+    {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet12']/speed", "value":"5000"},
+    {"xpath":"/test-acl:acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-test'][RULE_NAME='rule_20']/RULE_NAME",
+     "value":"rule_20"}
+  ],
+
+  "data_nodes":[
+	  {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']/alias",  "valid":"True"},
+          {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet20']/alias", "valid":"False"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE", "valid":"True"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST", "valid":"False"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='2000:f500:45:6709::/64']", "valid":"True"}
+  ],
+
+  "set_nodes":[
+          {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet10']/speed",  "value":"10000"},
+          {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']/mtu",     "value":"1500"},
+          {"xpath":"/test-vlan:vlan/VLAN/VLAN_LIST[vlanid='111']/description",      "value":"server_vlan111"}
+  ],
+
+  "node_values":[
+    {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']/speed",  "value":"25000"},
+    {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='2000:f500:45:6709::/64']/family",
+	   "value":"IPv6"}
+  ],
+
+  "schema_nodes":[
+     {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']/family",
+      "value":"/test-vlan:vlan/test-vlan:VLAN_INTERFACE/test-vlan:VLAN_INTERFACE_LIST/test-vlan:family"},
+     {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']/speed",
+      "value":"/test-port:port/test-port:PORT/test-port:PORT_LIST/test-port:speed"}
+  ],
+
+  "delete_nodes":[
+          {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet10']/speed",  "valid":"False"},
+          {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']/mtu",     "valid":"True"},
+          {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet20']/mtu",    "valid":"False"}
+  ],
+
+  "dependencies":[
+	  {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet8']/port_name",
+           "dependencies":
+                 ["/test-acl:acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V6']/ports[.='Ethernet8']",
+                  "/test-interface:interface/INTERFACE/INTERFACE_LIST[interface='Ethernet8'][ip-prefix='10.1.1.64/26']/interface",
+                  "/test-interface:interface/INTERFACE/INTERFACE_LIST[interface='Ethernet8'][ip-prefix='2000:f500:40:a749::/126']/interface"]}
+  ],
+  "schema_dependencies":[
+          {"xpath":"/test-port:port/test-port:PORT/test-port:PORT_LIST/test-port:port_name",
+           "schema_dependencies":
+                 ["/test-acl:acl/test-acl:ACL_TABLE/test-acl:ACL_TABLE_LIST/test-acl:ports",
+                  "/test-portchannel:portchannel/test-portchannel:PORTCHANNEL/test-portchannel:PORTCHANNEL_LIST/test-portchannel:members",
+                  "/test-interface:interface/test-interface:INTERFACE/test-interface:INTERFACE_LIST/test-interface:interface",
+                  "/test-vlan:vlan/test-vlan:VLAN_MEMBER/test-vlan:VLAN_MEMBER_LIST/test-vlan:port"]}
+  ],
+  "members":[
+	  {"xpath":"/test-port:port/PORT/PORT_LIST",
+           "members":
+		  ["/test-port:port/PORT/PORT_LIST[port_name='Ethernet0']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet1']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet2']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet3']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet4']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet5']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet6']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet7']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet8']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']",
+                   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet10']",
+		   "/test-port:port/PORT/PORT_LIST[port_name='Ethernet12']"]}
+  ],
+
+  "parents":[
+	  {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='2000:f500:45:6709::/64']/family",
+           "parent":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='2000:f500:45:6709::/64']"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']/scope",
+           "parent":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']/vlanid",
+           "parent":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']/ip-prefix",
+           "parent":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']"},
+          {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']/family",
+           "parent":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']"},
+	  {"xpath":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']/speed",
+           "parent":"/test-port:port/PORT/PORT_LIST[port_name='Ethernet9']"}
+ ],
+  "prefix":[
+    {"module_name":"test-head", "module_prefix":"head"},
+    {"module_name":"test-port", "module_prefix":"port"},
+    {"module_name":"test-acl",  "module_prefix":"acl"},
+    {"module_name":"test-interface", "module_prefix":"intf"},
+    {"module_name":"test-portchannel", "module_prefix":"lag"},
+    {"module_name":"test-vlan", "module_prefix":"vlan"}
+    ],
+  "data_type":[
+    {"xpath":"/test-port:port/test-port:PORT/test-port:PORT_LIST/test-port:port_name", "data_type":"LY_TYPE_STRING"},
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_INTERFACE/test-vlan:VLAN_INTERFACE_LIST/test-vlan:vlanid", "data_type":"LY_TYPE_LEAFREF"}
+    ],
+  "leafref_type":[
+    {"xpath":"/test-vlan:vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='2000:f500:45:6709::/64']/vlanid", "data_type":"LY_TYPE_UINT16"},
+    {"xpath":"/test-interface:interface/INTERFACE/INTERFACE_LIST[interface='Ethernet8'][ip-prefix='2000:f500:40:a749::/126']/interface", "data_type":"LY_TYPE_STRING"},
+    {"xpath":"/test-vlan:vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet0']/port", "data_type":"LY_TYPE_STRING"},
+    {"xpath":"/test-vlan:vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet0']/vlanid", "data_type":"LY_TYPE_UINT16"}
+   ],
+  "leafref_type_schema":[
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_INTERFACE/test-vlan:VLAN_INTERFACE_LIST/test-vlan:vlanid",
+     "data_type":"LY_TYPE_UINT16"},
+    {"xpath":"/test-interface:interface/test-interface:INTERFACE/test-interface:INTERFACE_LIST/test-interface:interface",
+     "data_type":"LY_TYPE_STRING"},
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_MEMBER/test-vlan:VLAN_MEMBER_LIST/test-vlan:port",
+     "data_type":"LY_TYPE_STRING"},
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_MEMBER/test-vlan:VLAN_MEMBER_LIST/test-vlan:vlanid",
+     "data_type":"LY_TYPE_UINT16"}
+   ],
+  "leafref_path":[
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_INTERFACE/test-vlan:VLAN_INTERFACE_LIST/test-vlan:vlanid",
+     "leafref_path":"../../../VLAN/VLAN_LIST/vlanid"},
+    {"xpath":"/test-interface:interface/test-interface:INTERFACE/test-interface:INTERFACE_LIST/test-interface:interface",
+     "leafref_path":"/test-port:port/test-port:PORT/test-port:PORT_LIST/test-port:port_name"},
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_MEMBER/test-vlan:VLAN_MEMBER_LIST/test-vlan:port",
+     "leafref_path":"/test-port:port/test-port:PORT/test-port:PORT_LIST/test-port:port_name"},
+    {"xpath":"/test-vlan:vlan/test-vlan:VLAN_MEMBER/test-vlan:VLAN_MEMBER_LIST/test-vlan:vlanid",
+     "leafref_path":"../../../VLAN/VLAN_LIST/vlanid"}
+   ]
+}

src/sonic-yang-mgmt/tests/libyang-python-tests/test_sonic_yang.py

@@ -0,0 +1,324 @@
+import sys
+import os
+import pytest
+import sonic_yang as sy
+import json
+import glob
+import logging
+from ijson import items as ijson_itmes
+
+test_path = os.path.dirname(os.path.abspath(__file__))
+modules_path = os.path.dirname(test_path)
+sys.path.insert(0, modules_path)
+
+logging.basicConfig(level=logging.DEBUG)
+log = logging.getLogger("YANG-TEST")
+log.setLevel(logging.INFO)
+log.addHandler(logging.NullHandler())
+
+class Test_SonicYang(object):
+    # class vars
+
+    @pytest.fixture(autouse=True, scope='class')
+    def data(self):
+        test_file = "./tests/libyang-python-tests/test_SonicYang.json"
+        data = self.jsonTestParser(test_file)
+        return data
+
+    @pytest.fixture(autouse=True, scope='class')
+    def yang_s(self, data):
+        yang_dir = str(data['yang_dir'])
+        yang_s = sy.SonicYang(yang_dir)
+        return yang_s
+
+    def jsonTestParser(self, file):
+        """
+        Open the json test file
+        """
+        with open(file) as data_file:
+            data = json.load(data_file)
+        return data
+
+    """
+        Get the JSON input based on func name
+        and return jsonInput
+    """
+    def readIjsonInput(self, yang_test_file, test):
+        try:
+            # load test specific Dictionary, using Key = func
+            # this is to avoid loading very large JSON in memory
+            print(" Read JSON Section: " + test)
+            jInput = ""
+            with open(yang_test_file, 'rb') as f:
+                jInst = ijson_itmes(f, test)
+                for it in jInst:
+                    jInput = jInput + json.dumps(it)
+        except Exception as e:
+            print("Reading Ijson failed")
+            raise(e)
+        return jInput
+
+    def setup_class(self):
+        pass
+
+    def load_yang_model_file(self, yang_s, yang_dir, yang_file, module_name):
+        yfile = yang_dir + yang_file
+        try:
+	    yang_s._load_schema_module(str(yfile))
+	except Exception as e:
+            print(e)
+            raise
+
+    #test load and get yang module
+    def test_load_yang_model_files(self, data, yang_s):
+        yang_dir = data['yang_dir']
+        for module in data['modules']:
+            file = str(module['file'])
+            module = str(module['module'])
+
+            self.load_yang_model_file(yang_s, yang_dir, file, module)
+            assert yang_s._get_module(module) is not None
+
+    #test load non-exist yang module file
+    def test_load_invalid_model_files(self, data, yang_s):
+        yang_dir = data['yang_dir']
+        file = "invalid.yang"
+        module = "invalid"
+
+        with pytest.raises(Exception):
+             assert self.load_yang_model_file(yang_s, yang_dir, file, module)
+
+    #test load yang modules in directory
+    def test_load_yang_model_dir(self, data, yang_s):
+        yang_dir = data['yang_dir']
+        yang_s._load_schema_modules(str(yang_dir))
+
+        for module_name in data['modules']:
+            assert yang_s._get_module(str(module_name['module'])) is not None
+
+    #test load yang modules and data files
+    def test_load_yang_model_data(self, data, yang_s):
+        yang_dir = str(data['yang_dir'])
+        yang_files = glob.glob(yang_dir+"/*.yang")
+        data_file = str(data['data_file'])
+        data_merge_file = str(data['data_merge_file'])
+
+        data_files = []
+        data_files.append(data_file)
+        data_files.append(data_merge_file)
+	print(yang_files)
+        yang_s._load_data_model(yang_dir, yang_files, data_files)
+
+        #validate the data tree from data_merge_file is loaded
+        for node in data['merged_nodes']:
+            xpath = str(node['xpath'])
+            value = str(node['value'])
+            val = yang_s._find_data_node_value(xpath)
+            assert str(val) == str(value)
+
+    #test load data file
+    def test_load_data_file(self, data, yang_s):
+        data_file = str(data['data_file'])
+        yang_s._load_data_file(data_file)
+
+    #test_validate_data_tree():
+    def test_validate_data_tree(self, data, yang_s):
+        yang_s.validate_data_tree()
+
+    #test find node
+    def test_find_node(self, data, yang_s):
+        for node in data['data_nodes']:
+            expected = node['valid']
+            xpath = str(node['xpath'])
+            dnode = yang_s._find_data_node(xpath)
+
+            if(expected == "True"):
+                 assert dnode is not None
+                 assert dnode.path() == xpath
+            else:
+                 assert dnode is None
+
+    #test add node
+    def test_add_node(self, data, yang_s):
+        for node in data['new_nodes']:
+            xpath = str(node['xpath'])
+            value = node['value']
+            yang_s._add_data_node(xpath, str(value))
+
+            data_node = yang_s._find_data_node(xpath)
+            assert data_node is not None
+
+    #test find node value
+    def test_find_data_node_value(self, data, yang_s):
+       for node in data['node_values']:
+            xpath = str(node['xpath'])
+            value = str(node['value'])
+            print(xpath)
+            print(value)
+            val = yang_s._find_data_node_value(xpath)
+            assert str(val) == str(value)
+
+    #test delete data node
+    def test_delete_node(self, data, yang_s):
+        for node in data['delete_nodes']:
+            xpath = str(node['xpath'])
+            yang_s._deleteNode(xpath)
+
+    #test set node's value
+    def test_set_datanode_value(self, data, yang_s):
+        for node in data['set_nodes']:
+            xpath = str(node['xpath'])
+            value = node['value']
+            yang_s._set_data_node_value(xpath, value)
+
+            val = yang_s._find_data_node_value(xpath)
+            assert str(val) == str(value)
+
+    #test list of members
+    def test_find_members(self, yang_s, data):
+        for node in data['members']:
+            members = node['members']
+            xpath = str(node['xpath'])
+            list = yang_s._find_data_nodes(xpath)
+            assert list.sort() == members.sort()
+
+    #get parent xpath
+    def test_get_parent_data_xpath(self, yang_s, data):
+        for node in data['parents']:
+            xpath = str(node['xpath'])
+            expected_xpath = str(node['parent'])
+            path = yang_s._get_parent_data_xpath(xpath)
+            assert path == expected_xpath
+
+    #test find_data_node_schema_xpath
+    def test_find_data_node_schema_xpath(self, yang_s, data):
+        for node in data['schema_nodes']:
+            xpath = str(node['xpath'])
+            schema_xpath = str(node['value'])
+            path = yang_s._find_data_node_schema_xpath(xpath)
+            assert path == schema_xpath
+
+    #test data dependencies
+    def test_find_data_dependencies(self, yang_s, data):
+        for node in data['dependencies']:
+            xpath = str(node['xpath'])
+            list = node['dependencies']
+            depend = yang_s.find_data_dependencies(xpath)
+            assert set(depend) == set(list)
+
+    #test data dependencies
+    def test_find_schema_dependencies(self, yang_s, data):
+        for node in data['schema_dependencies']:
+            xpath = str(node['xpath'])
+            list = node['schema_dependencies']
+            depend = yang_s._find_schema_dependencies(xpath)
+            assert set(depend) == set(list)
+
+    #test merge data tree
+    def test_merge_data_tree(self, data, yang_s):
+        data_merge_file = data['data_merge_file']
+        yang_dir = str(data['yang_dir'])
+        yang_s._merge_data(data_merge_file, yang_dir)
+        #yang_s.root.print_mem(ly.LYD_JSON, ly.LYP_FORMAT)
+
+    #test get module prefix
+    def test_get_module_prefix(self, yang_s, data):
+        for node in data['prefix']:
+            xpath = str(node['module_name'])
+            expected = node['module_prefix']
+            prefix = yang_s._get_module_prefix(xpath)
+            assert expected == prefix
+
+    #test get data type
+    def test_get_data_type(self, yang_s, data):
+        for node in data['data_type']:
+            xpath = str(node['xpath'])
+            expected = node['data_type']
+            expected_type = yang_s._str_to_type(expected)
+            data_type = yang_s._get_data_type(xpath)
+            assert expected_type == data_type
+
+    def test_get_leafref_type(self, yang_s, data):
+        for node in data['leafref_type']:
+            xpath = str(node['xpath'])
+            expected = node['data_type']
+            expected_type = yang_s._str_to_type(expected)
+            data_type = yang_s._get_leafref_type(xpath)
+            assert expected_type == data_type
+
+    def test_get_leafref_path(self, yang_s, data):
+        for node in data['leafref_path']:
+            xpath = str(node['xpath'])
+            expected_path = node['leafref_path']
+            path = yang_s._get_leafref_path(xpath)
+            assert expected_path == path
+
+    def test_get_leafref_type_schema(self, yang_s, data):
+        for node in data['leafref_type_schema']:
+            xpath = str(node['xpath'])
+            expected = node['data_type']
+            expected_type = yang_s._str_to_type(expected)
+            data_type = yang_s._get_leafref_type_schema(xpath)
+            assert expected_type == data_type
+
+    """
+    This is helper function to load YANG models for tests cases, which works
+    on Real SONiC Yang models. Mainly tests  for translation and reverse
+    translation.
+    """
+    @pytest.fixture(autouse=True, scope='class')
+    def sonic_yang_data(self):
+        sonic_yang_dir = "../sonic-yang-models/yang-models/"
+        sonic_yang_test_file = "../sonic-yang-models/tests/yang_model_tests/yangTest.json"
+
+        syc = sy.SonicYang(sonic_yang_dir)
+        syc.loadYangModel()
+
+        sonic_yang_data = dict()
+        sonic_yang_data['yang_dir'] = sonic_yang_dir
+        sonic_yang_data['test_file'] = sonic_yang_test_file
+        sonic_yang_data['syc'] = syc
+
+        return sonic_yang_data
+
+    def test_xlate_rev_xlate(self, sonic_yang_data):
+        # In this test, xlation and revXlation is tested with latest Sonic
+        # YANG model.
+        test_file = sonic_yang_data['test_file']
+        syc = sonic_yang_data['syc']
+
+        jIn = self.readIjsonInput(test_file, 'SAMPLE_CONFIG_DB_JSON')
+
+        syc.loadData(json.loads(jIn))
+
+        # TODO: Make sure no extra table is loaded
+
+        syc.getData()
+
+        if syc.jIn and syc.jIn == syc.revXlateJson:
+            print("Xlate and Rev Xlate Passed")
+        else:
+            print("Xlate and Rev Xlate failed")
+            # make it fail
+            assert False == True
+
+        return
+
+    def test_table_with_no_yang(self, sonic_yang_data):
+        # in this test, tables with no YANG models must be stored seperately
+        # by this library.
+        test_file = sonic_yang_data['test_file']
+        syc = sonic_yang_data['syc']
+
+        jIn = self.readIjsonInput(test_file, 'SAMPLE_CONFIG_DB_JSON_1')
+
+        syc.loadData(json.loads(jIn))
+
+        ty = syc.tablesWithOutYang
+
+        assert (len(ty) and "UNKNOWN_TABLE" in ty)
+
+        return
+
+    def teardown_class(self):
+        pass

src/sonic-yang-mgmt/tests/test_sonic_yang_mgmt.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""Tests for `sonic_yang_mgmt` package."""
+
+import pytest
+
+@pytest.fixture
+def response():
+    """Sample pytest fixture.
+
+    See more at: http://doc.pytest.org/en/latest/fixture.html
+    """
+    # import requests
+    # return requests.get('https://github.com/audreyr/cookiecutter-pypackage')
+
+
+def test_content(response):
+    """Sample pytest test function with the pytest fixture as an argument."""
+    # from bs4 import BeautifulSoup
+    # assert 'GitHub' in BeautifulSoup(response.content).title.string

src/sonic-yang-models/tests/yang_model_tests/yangTest.json

@@ -1275,10 +1275,76 @@
 				"family": "IPv4"
 			}
 		},
+        "BREAKOUT_CFG": {
+            "Ethernet0": {
+                "brkout_mode": "1x100G[40G]"
+            },
+            "Ethernet4": {
+                "brkout_mode": "4x25G"
+            },
+            "Ethernet8": {
+                "brkout_mode": "1x100G[40G]"
+            }
+        },
+        "VERSIONS": {
+            "DATABASE": {
+                "VERSION": "version_1_0_3"
+            }
+        },
+        "FLEX_COUNTER_TABLE": {
+            "PFCWD": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "PG_WATERMARK": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "PORT": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "QUEUE": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "QUEUE_WATERMARK": {
+                "FLEX_COUNTER_STATUS": "enable"
+            }
+        },
         "CRM": {
             "Config": {
+                "acl_counter_high_threshold": "85",
+                "acl_counter_low_threshold": "70",
+                "acl_counter_threshold_type": "percentage",
                 "polling_interval": "0"
             }
         }
+    },
+    "SAMPLE_CONFIG_DB_JSON_1": {
+        "FLEX_COUNTER_TABLE": {
+            "PFCWD": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "PG_WATERMARK": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "PORT": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "QUEUE": {
+                "FLEX_COUNTER_STATUS": "enable"
+            },
+            "QUEUE_WATERMARK": {
+                "FLEX_COUNTER_STATUS": "enable"
+            }
+        },
+        "CRM": {
+            "Config": {
+                "acl_counter_high_threshold": "85",
+                "acl_counter_low_threshold": "70",
+                "acl_counter_threshold_type": "percentage",
+                "polling_interval": "0"
+            }
+        },
+        "UNKNOWN_TABLE": {
+            "Error": "This Table is for testing, This Table does not have YANG models."
+        }
     }
 }