Add API endpoint for retrieving capabilities

This endpoint will serve as a proxy for the openstack/defcore
repository. Instead of the UI sending requests to GitHub directly
where requests might be impeded due to cross-origin blockage or API
rate-limiting, the UI will be able to send requests to the Refstack
API in order to get capability data. The requests-cache library is
used so as not to keep sending requests to GitHub when likely
nothing has changed. With this, Refstack no longer has to worry about
mirroring capability files and keeping them updated.

GET /v1/capabilities - list all capability files
GET /v1/capabilities/2015.03 - get contents of file 2015.03.json

Change-Id: I6d327273f191e3339219e35eed8768da35c5bffb

refstack/tests/unit/test_api.py

@@ -15,9 +15,14 @@
 
 """Tests for API's controllers"""
 
+import json
+import sys
+
+import httmock
 import mock
 from oslo_config import fixture as config_fixture
 from oslotest import base
+import requests
 
 from refstack.api import constants as const
 from refstack.api import utils as api_utils
@@ -25,6 +30,15 @@ from refstack.api.controllers import root
 from refstack.api.controllers import v1
 
 
+def safe_json_dump(content):
+    if isinstance(content, (dict, list)):
+        if sys.version_info[0] == 3:
+            content = bytes(json.dumps(content), 'utf-8')
+        else:
+            content = json.dumps(content)
+    return content
+
+
 class RootControllerTestCase(base.BaseTestCase):
 
     def test_index(self):
@@ -230,6 +244,81 @@ class ResultsControllerTestCase(base.BaseTestCase):
         db_get_test.assert_called_once_with(page_number, per_page, filters)
 
 
+class CapabilitiesControllerTestCase(base.BaseTestCase):
+
+    def setUp(self):
+        super(CapabilitiesControllerTestCase, self).setUp()
+        self.controller = v1.CapabilitiesController()
+
+    def test_get_capabilities(self):
+        """Test when getting a list of all capability files."""
+        @httmock.all_requests
+        def github_api_mock(url, request):
+            headers = {'content-type': 'application/json'}
+            content = [{'name': '2015.03.json', 'type': 'file'},
+                       {'name': '2015.next.json', 'type': 'file'},
+                       {'name': '2015.03', 'type': 'dir'}]
+            content = safe_json_dump(content)
+            return httmock.response(200, content, headers, None, 5, request)
+
+        with httmock.HTTMock(github_api_mock):
+            result = self.controller.get()
+        self.assertEqual(['2015.03.json'], result)
+
+    @mock.patch('pecan.abort')
+    def test_get_capabilities_error_code(self, mock_abort):
+        """Test when the HTTP status code isn't a 200 OK. The status should
+           be propogated."""
+        @httmock.all_requests
+        def github_api_mock(url, request):
+            content = {'title': 'Not Found'}
+            return httmock.response(404, content, None, None, 5, request)
+
+        with httmock.HTTMock(github_api_mock):
+            self.controller.get()
+        mock_abort.assert_called_with(404)
+
+    @mock.patch('requests.get')
+    @mock.patch('pecan.abort')
+    def test_get_capabilities_exception(self, mock_abort, mock_request):
+        """Test when the GET request raises an exception."""
+        mock_request.side_effect = requests.exceptions.RequestException()
+        self.controller.get()
+        mock_abort.assert_called_with(500)
+
+    def test_get_capability_file(self):
+        """Test when getting a specific capability file"""
+        @httmock.all_requests
+        def github_mock(url, request):
+            content = {'foo': 'bar'}
+            return httmock.response(200, content, None, None, 5, request)
+
+        with httmock.HTTMock(github_mock):
+            result = self.controller.get_one('2015.03')
+        self.assertEqual({'foo': 'bar'}, result)
+
+    @mock.patch('pecan.abort')
+    def test_get_capability_file_error_code(self, mock_abort):
+        """Test when the HTTP status code isn't a 200 OK. The status should
+           be propogated."""
+        @httmock.all_requests
+        def github_api_mock(url, request):
+            content = {'title': 'Not Found'}
+            return httmock.response(404, content, None, None, 5, request)
+
+        with httmock.HTTMock(github_api_mock):
+            self.controller.get_one('2010.03')
+        mock_abort.assert_called_with(404)
+
+    @mock.patch('requests.get')
+    @mock.patch('pecan.abort')
+    def test_get_capability_file_exception(self, mock_abort, mock_request):
+        """Test when the GET request raises an exception."""
+        mock_request.side_effect = requests.exceptions.RequestException()
+        self.controller.get_one('2010.03')
+        mock_abort.assert_called_with(500)
+
+
 class BaseRestControllerWithValidationTestCase(base.BaseTestCase):
 
     def setUp(self):