Unit test for asserting correct url in list_services

This commit enhances check_service_client_function with a new
arg called ``mock_args`` which can be used to assert that function2mock
was called with args/kwargs passed to ``mock_args``.

A docstring was added to check_service_client_function which includes
information for ``mock_args``:

:param mock_args: List/dict of expected args/kwargs called by
       function2mock. For example: If mock_args=['foo'] then
       ``assert_called_once_with('foo')`` is called. If
       mock_args={'foo': 'bar'} then
       ``assert_called_once_with(foo='bar')`` is called.

This means that more robust service client testing can be performed
to avoid errors in [0] from happening. This approach can also be
extended to not only self.get -- but also to self.post or self.put and
so entire payloads to the clients can be validated via unit testing.

An alternative (but worse) implementation is this:

    @mock.patch.object(services_client, 'urllib')
    def test_list_services_with_params(self, mock_urllib):
        self._test_list_services(type='fake-type')
        mock_urllib.urlencode.assert_called_once_with(
            {'type': 'fake-type'})

but all this does is assert that the params are url-encoded. It does
nothing to assert that self.get, for example, is actually called with
the right URL.

[0] I2e2ebb72732ab95d5f9c1d988037c5e263bf2a71

Change-Id: Ib066add5ff09bd3b32b293833ed6b7a3d5b43955
diff --git a/tempest/tests/lib/services/base.py b/tempest/tests/lib/services/base.py
index 71b7f2d..90c9f63 100644
--- a/tempest/tests/lib/services/base.py
+++ b/tempest/tests/lib/services/base.py
@@ -31,12 +31,42 @@
 
     def check_service_client_function(self, function, function2mock,
                                       body, to_utf=False, status=200,
-                                      headers=None, **kwargs):
+                                      headers=None, mock_args=None,
+                                      **kwargs):
+        """Mock a service client function for unit testing.
+
+        :param function: The service client function to call.
+        :param function2mock: The REST call to mock inside the service client
+               function.
+        :param body: Expected response body returned by the service client
+               function.
+        :param to_utf: Whether to use UTF-8 encoding for request.
+        :param status: Expected response status returned by the service client
+               function.
+        :param headers: Expected headers returned by the service client
+               function.
+        :param mock_args: List/dict/value of expected args/kwargs called by
+               function2mock. For example:
+               * If mock_args=['foo'] then ``assert_called_once_with('foo')``
+                 is called.
+               * If mock_args={'foo': 'bar'} then
+                 ``assert_called_once_with(foo='bar')`` is called.
+               * If mock_args='foo' then ``assert_called_once_with('foo')``
+                 is called.
+        :param kwargs: kwargs that are passed to function.
+        """
         mocked_response = self.create_response(body, to_utf, status, headers)
-        self.useFixture(fixtures.MockPatch(
+        fixture = self.useFixture(fixtures.MockPatch(
             function2mock, return_value=mocked_response))
         if kwargs:
             resp = function(**kwargs)
         else:
             resp = function()
         self.assertEqual(body, resp)
+
+        if isinstance(mock_args, list):
+            fixture.mock.assert_called_once_with(*mock_args)
+        elif isinstance(mock_args, dict):
+            fixture.mock.assert_called_once_with(**mock_args)
+        elif mock_args is not None:
+            fixture.mock.assert_called_once_with(mock_args)
diff --git a/tempest/tests/lib/services/identity/v3/test_services_client.py b/tempest/tests/lib/services/identity/v3/test_services_client.py
index f87fcce..b464644 100644
--- a/tempest/tests/lib/services/identity/v3/test_services_client.py
+++ b/tempest/tests/lib/services/identity/v3/test_services_client.py
@@ -101,12 +101,15 @@
             bytes_body,
             service_id="686766")
 
-    def _test_list_services(self, bytes_body=False):
+    def _test_list_services(self, bytes_body=False, mock_args='services',
+                            **params):
         self.check_service_client_function(
             self.client.list_services,
             'tempest.lib.common.rest_client.RestClient.get',
             self.FAKE_LIST_SERVICES,
-            bytes_body)
+            bytes_body,
+            mock_args=[mock_args],
+            **params)
 
     def _test_update_service(self, bytes_body=False):
         self.check_service_client_function(
@@ -134,6 +137,10 @@
     def test_list_services_with_bytes_body(self):
         self._test_list_services(bytes_body=True)
 
+    def test_list_services_with_params(self):
+        self._test_list_services(
+            type='fake-type', mock_args='services?type=fake-type')
+
     def test_update_service_with_str_body(self):
         self._test_update_service()