[test] Adding platform.json configuration file unit test (#3911)

- What I did
In order to allow the SONiC community to check in platform capability file i.e. platform.json
file directly under device folder. We need to add this test to make sure the contents of the this file is compliant with platform capability design specified in DPB HLD doc

- How I did it
Added platformJson_checker.py file in Test folder.

Signed-off-by: Sangita Maity <sangitamaity0211@gmail.com>

src/sonic-device-data/src/Makefile

@@ -11,4 +11,7 @@ test:
 	for f in $$(find ../../../device -name media_settings.json); do
 	    ./media_checker $$f
 	done
+	for f in $$(find ../../../device -name platform.json); do
+	    ./platform_json_checker $$f
+	done
 	popd

src/sonic-device-data/tests/media_checker

@@ -138,7 +138,7 @@ def main(argv):
 
     # Load target file
     if len(argv) == 0:
-        files = glob.glob('*.json')
+        files = glob.glob('*media_settings.json')
     else:
         files = argv
 

src/sonic-device-data/tests/platform_json_checker

@@ -0,0 +1,99 @@
+#!/usr/bin/env python
+try:
+    import re
+    import sys
+    import glob
+    import json
+except ImportError as e:
+    raise ImportError (str(e) + "- required module not found")
+
+# TODO: need to remove basestring once migrate to Python 3 and just change to str
+try:
+    basestring
+except NameError:
+    basestring = str
+
+# Global variable
+PORT_ATTRIBUTES = ["index", "lanes", "alias_at_lanes", "breakout_modes"]
+ATTR_LEN = len(PORT_ATTRIBUTES)
+PORT_REG = "Ethernet(\d+)"
+PLATFORM_JSON = '*platform.json'
+INTF_KEY = "interfaces"
+
+def usage():
+    print "Usage: " + sys.argv[0] + " <platform_json_file>"
+    sys.exit(1)
+
+def check_port_attr(port_attr):
+    for each_key in port_attr:
+        if each_key not in PORT_ATTRIBUTES:
+            print "Error: "+ each_key + " is not the correct Port attribute."
+            return False
+        if not port_attr[each_key]:
+            print "Error: "+ each_key + " has no value."
+            return False
+        # TODO: need to remove basestring once migrate to Python 3 and just change to str
+        if not isinstance(port_attr[each_key], basestring):
+            print "Error:value type of  "+ each_key + " must be string."
+            return False
+    return True
+
+def check_file(platform_json_file):
+    try:
+        platform_cap_file = open(platform_json_file,"r")
+        platform_file_data = platform_cap_file.read()
+        port_dict = json.loads(platform_file_data)
+
+        for each_port in port_dict[INTF_KEY]:
+            # Validate port at top level
+            port_id = re.search(PORT_REG, each_port)
+            if port_id is  None:
+                print "Error: Unknown Interface " + str(each_port) + " at top level"
+                return False
+
+            total_attr = len(port_dict[INTF_KEY][each_port].keys())
+            port_attr = port_dict[INTF_KEY][each_port]
+
+            if total_attr != ATTR_LEN:
+                missing_attr = ', '.join(set(PORT_ATTRIBUTES).difference(list(port_attr)))
+                print "Error: " + missing_attr + " of " + each_port + " is/are missing"
+                return False
+
+            #Validate port attributes for each port
+            if not check_port_attr(port_attr):
+                return False
+    except IOError:
+        print "Error: Cannot open file " + platform_json_file
+        return False
+    except ValueError,e:
+        print "Error in parsing json file " + platform_json_file + " "
+        print str(e)
+        return False
+    return True
+
+def main(argv):
+    if len(argv) > 0 and argv[0] == "-h":
+        usage()
+
+    # Load target file
+    if len(argv) == 0:
+        files = glob.glob(PLATFORM_JSON)
+    else:
+        files = argv
+
+    all_good = True
+
+    for f in files:
+        good = check_file(f)
+        if good:
+            print "File " + f + " passed validity check"
+        else:
+            print "File " + f + " failed validity check"
+
+        all_good = all_good and good
+
+    if not all_good:
+        sys.exit(-1)
+
+if __name__ == "__main__":
+    main(sys.argv[1:])