use random ports for api and callback services

tests/api/v1/generator/func.py

@@ -1,5 +1,6 @@
 from .base_case import TestCaseMixin
 import os
+import socket
 import unittest
 
 
@@ -24,8 +25,8 @@ def _create_and_attach_test_case(target_module, test_case_directory,
 
 def _create_test_case(test_case_directory, test_case_name):
     class_dict = {
-        'api_port': 8822,
-        'callback_port': 2288,
+        'api_port': _get_available_port(),
+        'callback_port': _get_available_port(),
         'directory': os.path.join(test_case_directory, test_case_name),
         'test_name': test_case_name,
     }
@@ -35,3 +36,12 @@ def _create_test_case(test_case_directory, test_case_name):
 
 def _attach_test_case(target_module, test_case):
     setattr(target_module, test_case.__name__, test_case)
+
+
+def _get_available_port():
+    s = socket.socket()
+    s.bind(('127.0.0.1', 0))
+    port = s.getsockname()[1]
+    s.close()
+
+    return port