Add to_str method in python client and add test cases.

samples/client/petstore/python/tests/test_pet_model.py

@@ -0,0 +1,40 @@
+# coding: utf-8
+
+"""
+Run the tests.
+$ pip install nose (optional)
+$ cd swagger_client-python
+$ nosetests -v
+"""
+
+import os
+import time
+import unittest
+
+import swagger_client
+
+
+class PetModelTests(unittest.TestCase):
+
+    def setUp(self):
+        self.pet = swagger_client.Pet()
+        self.pet.name = "test name"
+        self.pet.id = 1
+        self.pet.photo_urls = ["string"]
+        self.pet.status = "available"
+        cate = swagger_client.Category()
+        cate.id = 1
+        cate.name = "dog"
+        self.pet.category = cate
+        tag = swagger_client.Tag()
+        tag.id = 1
+        self.pet.tags = [tag]
+
+    def test_to_str(self):
+        data = ("{'category': {'id': 1, 'name': 'dog'},\n"
+                " 'id': 1,\n"
+                " 'name': 'test name',\n"
+                " 'photo_urls': ['string'],\n"
+                " 'status': 'available',\n"
+                " 'tags': [{'id': 1, 'name': None}]}")
+        self.assertEqual(data, self.pet.to_str())