updated ApiClient of python sdk.

When create api instance, if we don't pass the `api_client` parameter,
then use the default api_client in `config` module.

modules/swagger-codegen/src/main/java/com/wordnik/swagger/codegen/languages/PythonClientCodegen.java

@@ -71,6 +71,7 @@ public class PythonClientCodegen extends DefaultCodegen implements CodegenConfig
     supportingFiles.add(new SupportingFile("swagger.mustache", invokerPackage, "swagger.py"));
     supportingFiles.add(new SupportingFile("rest.mustache", invokerPackage, "rest.py"));
     supportingFiles.add(new SupportingFile("util.mustache", invokerPackage, "util.py"));
+    supportingFiles.add(new SupportingFile("config.mustache", invokerPackage, "config.py"));
     supportingFiles.add(new SupportingFile("__init__package.mustache", invokerPackage, "__init__.py"));
     supportingFiles.add(new SupportingFile("__init__model.mustache", modelPackage.replace('.', File.separatorChar), "__init__.py"));
     supportingFiles.add(new SupportingFile("__init__api.mustache", apiPackage.replace('.', File.separatorChar), "__init__.py"));

modules/swagger-codegen/src/main/resources/python/api.mustache

@@ -31,11 +31,16 @@ from ..util import remove_none
 
 from ..swagger import ApiClient
 
+from .. import config
+
 {{#operations}}
 class {{classname}}(object):
 
-    def __init__(self, api_client):
+    def __init__(self, api_client=None):
-        self.api_client = api_client
+        if api_client:
+            self.api_client = api_client
+        else:
+            self.api_client = config.api_client
     {{#operation}}
     def {{nickname}}(self, {{#allParams}}{{#required}}{{paramName}}, {{/required}}{{/allParams}}**kwargs):
         """

modules/swagger-codegen/src/main/resources/python/config.mustache

@@ -0,0 +1,8 @@
+from __future__ import absolute_import
+
+from .swagger import ApiClient
+
+# Configuration variables
+
+api_client = ApiClient("{{basePath}}")
+

samples/client/petstore/python/SwaggerPetstore-python/SwaggerPetstore/apis/pet_api.py

@@ -31,10 +31,15 @@ from ..util import remove_none
 
 from ..swagger import ApiClient
 
+from .. import config
+
 class PetApi(object):
 
-    def __init__(self, api_client):
+    def __init__(self, api_client=None):
-        self.api_client = api_client
+        if api_client:
+            self.api_client = api_client
+        else:
+            self.api_client = config.api_client
     
     def update_pet(self, **kwargs):
         """

samples/client/petstore/python/SwaggerPetstore-python/SwaggerPetstore/apis/store_api.py

@@ -31,10 +31,15 @@ from ..util import remove_none
 
 from ..swagger import ApiClient
 
+from .. import config
+
 class StoreApi(object):
 
-    def __init__(self, api_client):
+    def __init__(self, api_client=None):
-        self.api_client = api_client
+        if api_client:
+            self.api_client = api_client
+        else:
+            self.api_client = config.api_client
     
     def get_inventory(self, **kwargs):
         """

samples/client/petstore/python/SwaggerPetstore-python/SwaggerPetstore/apis/user_api.py

@@ -31,10 +31,15 @@ from ..util import remove_none
 
 from ..swagger import ApiClient
 
+from .. import config
+
 class UserApi(object):
 
-    def __init__(self, api_client):
+    def __init__(self, api_client=None):
-        self.api_client = api_client
+        if api_client:
+            self.api_client = api_client
+        else:
+            self.api_client = config.api_client
     
     def create_user(self, **kwargs):
         """

samples/client/petstore/python/SwaggerPetstore-python/SwaggerPetstore/config.py

@@ -0,0 +1,8 @@
+from __future__ import absolute_import
+
+from .swagger import ApiClient
+
+# Configuration variables
+
+api_client = ApiClient("http://petstore.swagger.io/v2")
+

samples/client/petstore/python/SwaggerPetstore-python/tests/test_pet_api.py

@@ -13,6 +13,7 @@ import unittest
 
 import SwaggerPetstore
 from SwaggerPetstore.rest import ErrorResponse
+from SwaggerPetstore import config
 
 HOST = 'http://petstore.swagger.io/v2'
 
@@ -49,6 +50,26 @@ class PetApiTests(unittest.TestCase):
         self.test_file_dir = os.path.realpath(self.test_file_dir)
         self.foo = os.path.join(self.test_file_dir, "foo.png")
 
+    def test_create_api_instance(self):
+        pet_api = SwaggerPetstore.PetApi()
+        pet_api2 = SwaggerPetstore.PetApi()
+        api_client3 = SwaggerPetstore.ApiClient()
+        api_client3.user_agent = 'api client 3'
+        api_client4 = SwaggerPetstore.ApiClient()
+        api_client4.user_agent = 'api client 4'
+        pet_api3 = SwaggerPetstore.PetApi(api_client3)
+
+        # same default api client
+        self.assertEqual(pet_api.api_client, pet_api2.api_client)
+        # confirm using the default api client in the config module
+        self.assertEqual(pet_api.api_client, config.api_client)
+        # 2 different api clients are not the same
+        self.assertNotEqual(api_client3, api_client4)
+        # customized pet api not using the default api client
+        self.assertNotEqual(pet_api3.api_client, config.api_client)
+        # customized pet api not using the old pet api's api client
+        self.assertNotEqual(pet_api3.api_client, pet_api2.api_client)
+
     def test_add_pet_and_get_pet_by_id(self):
         self.pet_api.add_pet(body=self.pet)