Load user capabilities from Pillar config and allow extensions to extend.

Default caps can be overridden using the USER_CAPABILITIES name in
config_local.py. These can be extended by Pillar Extensions.

tests/test_user_capabilities.py

@@ -0,0 +1,70 @@
+from pillar.tests import PillarTestServer, AbstractPillarTest
+
+
+class UserCapsTestServer(PillarTestServer):
+    def __init__(self, *args, **kwargs):
+        PillarTestServer.__init__(self, *args, **kwargs)
+
+        from pillar.extension import PillarExtension
+
+        # Late-declare this class, so that it is recreated for each unit test.
+        class UserCapsTestExtension(PillarExtension):
+            user_roles = {
+                'test-user',
+                'test-မျောက်',
+            }
+            user_caps = {
+                'subscriber': {'extra-sub-cap', 'another-cap'},
+                'test-user': {'test-user-cap-1', 'နဂါးမောက်သီး'},
+                'test-မျောက်': {'test-monkey-cap-1', 'နဂါးမောက်သီး'},
+            }
+
+            @property
+            def name(self):
+                return 'test_user_caps'
+
+            def flask_config(self):
+                return {}
+
+            def eve_settings(self):
+                return {}
+
+            def blueprints(self):
+                return []
+
+        self.load_extension(UserCapsTestExtension(), '/user-caps-test')
+
+
+class UserCapsTest(AbstractPillarTest):
+    pillar_server_class = UserCapsTestServer
+
+    def setUp(self, **kwargs):
+        super().setUp(**kwargs)
+
+    def tearDown(self):
+        super().tearDown()
+
+    def test_default_caps(self):
+        app_caps = self.app.user_caps
+
+        self.assertEqual(app_caps['demo'], frozenset({
+            'subscriber', 'home-project'
+        }))
+
+    def test_aggr_caps_merged_subscriber(self):
+        app_caps = self.app.user_caps
+
+        self.assertEqual(app_caps['subscriber'], frozenset({
+            'subscriber', 'home-project', 'extra-sub-cap', 'another-cap'
+        }))
+
+    def test_aggr_caps_new_roles(self):
+        app_caps = self.app.user_caps
+
+        self.assertEqual(app_caps['test-user'], frozenset({
+            'test-user-cap-1', 'နဂါးမောက်သီး'
+        }))
+
+        self.assertEqual(app_caps['test-မျောက်'], frozenset({
+            'test-monkey-cap-1', 'နဂါးမောက်သီး'
+        }))