Add app providers, tests, docs

tests/test_app.py

@@ -20,6 +20,7 @@ class TestAppHandler(TestCase):
     def setUp(self):
         self.config = WuttaConfig(appname='wuttatest')
         self.app = app.AppHandler(self.config)
+        self.config.app = self.app
 
     def test_init(self):
         self.assertIs(self.app.config, self.config)
@@ -109,3 +110,81 @@ class TestAppHandler(TestCase):
         session.execute(sa.text("insert into setting values ('foo', 'bar');"))
         value = self.app.get_setting(session, 'foo')
         self.assertEqual(value, 'bar')
+
+
+class TestAppProvider(TestCase):
+
+    def setUp(self):
+        self.config = WuttaConfig(appname='wuttatest')
+        self.app = app.AppHandler(self.config)
+        self.config.app = self.app
+
+    def test_constructor(self):
+
+        # config object is expected
+        provider = app.AppProvider(self.config)
+        self.assertIs(provider.config, self.config)
+        self.assertIs(provider.app, self.app)
+
+        # but can pass app handler instead
+        provider = app.AppProvider(self.app)
+        self.assertIs(provider.config, self.config)
+        self.assertIs(provider.app, self.app)
+
+    def test_get_all_providers(self):
+
+        class FakeProvider(app.AppProvider):
+            pass
+
+        # nb. we specify *classes* here
+        fake_providers = {'fake': FakeProvider}
+
+        with patch('wuttjamaican.app.load_entry_points') as load_entry_points:
+            load_entry_points.return_value = fake_providers
+
+            # sanity check, we get *instances* back from this
+            providers = self.app.get_all_providers()
+            load_entry_points.assert_called_once_with('wuttatest.providers')
+            self.assertEqual(len(providers), 1)
+            self.assertIn('fake', providers)
+            self.assertIsInstance(providers['fake'], FakeProvider)
+
+    def test_hasattr(self):
+
+        class FakeProvider(app.AppProvider):
+            def fake_foo(self):
+                pass
+
+        self.app.providers = {'fake': FakeProvider(self.config)}
+
+        self.assertTrue(hasattr(self.app, 'fake_foo'))
+        self.assertFalse(hasattr(self.app, 'fake_method_does_not_exist'))
+
+    def test_getattr(self):
+
+        class FakeProvider(app.AppProvider):
+            def fake_foo(self):
+                return 42
+
+        # nb. using instances here
+        fake_providers = {'fake': FakeProvider(self.config)}
+
+        with patch.object(self.app, 'get_all_providers') as get_all_providers:
+            get_all_providers.return_value = fake_providers
+
+            self.assertNotIn('providers', self.app.__dict__)
+            self.assertIs(self.app.providers, fake_providers)
+            get_all_providers.assert_called_once_with()
+
+    def test_getattr_providers(self):
+
+        # collection of providers is loaded on demand
+        self.assertNotIn('providers', self.app.__dict__)
+        self.assertIsNotNone(self.app.providers)
+
+        # custom attr does not exist yet
+        self.assertRaises(AttributeError, getattr, self.app, 'foo_value')
+
+        # but provider can supply the attr
+        self.app.providers['mytest'] = MagicMock(foo_value='bar')
+        self.assertEqual(self.app.foo_value, 'bar')