Add a unit test for __str__() of rest_client

This commit adds a unit test for __str__() of rest_client.

Change-Id: I3402903277250924862c0aef468b98dcdf860ad6

tempest_lib/tests/fake_auth_provider.py

@@ -22,6 +22,9 @@ class FakeAuthProvider(object):
     def auth_request(self, method, url, headers=None, body=None, filters=None):
         return url, headers, body
 
+    def base_url(self, filters, auth_data=None):
+        return "https://example.com"
+
 
 class FakeCredentials(object):
 

tempest_lib/tests/test_rest_client.py

@@ -31,8 +31,9 @@ class BaseRestClientTestClass(base.TestCase):
 
     def setUp(self):
         super(BaseRestClientTestClass, self).setUp()
+        self.fake_auth_provider = fake_auth_provider.FakeAuthProvider()
         self.rest_client = rest_client.RestClient(
-            fake_auth_provider.FakeAuthProvider(), None, None)
+            self.fake_auth_provider, None, None)
         self.stubs.Set(httplib2.Http, 'request', self.fake_http.request)
         self.useFixture(mockpatch.PatchObject(self.rest_client,
                                               '_log_request'))
@@ -442,6 +443,13 @@ class TestRestClientUtils(BaseRestClientTestClass):
         actual_resp, actual_versions = self.rest_client.get_versions()
         self.assertEqual(['v1', 'v2'], list(actual_versions))
 
+    def test__str__(self):
+        def get_token():
+            return "deadbeef"
+
+        self.fake_auth_provider.get_token = get_token
+        self.assertIsNotNone(str(self.rest_client))
+
 
 class TestProperties(BaseRestClientTestClass):