feat: add basic theme system

This is intended to allow override of look/feel without overriding the
logic/structure of templates.  In practice the main goal internally is
to allow testing of Vue 3 + Oruga, to eventually replace Vue 2 + Buefy
as the default theme.

tests/test_subscribers.py

@@ -41,13 +41,21 @@ class TestNewRequest(TestCase):
         self.assertIs(self.request.wutta_config, self.config)
 
     def test_use_oruga_default(self):
-        event = MagicMock(request=self.request)
 
         # request gets a new attr, false by default
         self.assertFalse(hasattr(self.request, 'use_oruga'))
+        event = MagicMock(request=self.request)
         subscribers.new_request(event)
         self.assertFalse(self.request.use_oruga)
 
+        # nb. using 'butterfly' theme should cause the 'use_oruga'
+        # flag to be turned on by default
+        self.request = self.make_request()
+        self.request.registry.settings['wuttaweb.theme'] = 'butterfly'
+        event = MagicMock(request=self.request)
+        subscribers.new_request(event)
+        self.assertTrue(self.request.use_oruga)
+
     def test_use_oruga_custom(self):
         self.config.setdefault('wuttaweb.oruga_detector.spec', 'tests.test_subscribers:custom_oruga_detector')
         event = MagicMock(request=self.request)
@@ -57,6 +65,26 @@ class TestNewRequest(TestCase):
         subscribers.new_request(event)
         self.assertTrue(self.request.use_oruga)
 
+    def test_register_component(self):
+        event = MagicMock(request=self.request)
+        subscribers.new_request(event)
+
+        # component tracking dict is missing at first
+        self.assertFalse(hasattr(self.request, '_wuttaweb_registered_components'))
+
+        # registering a component
+        self.request.register_component('foo-example', 'FooExample')
+        self.assertTrue(hasattr(self.request, '_wuttaweb_registered_components'))
+        self.assertEqual(len(self.request._wuttaweb_registered_components), 1)
+        self.assertIn('foo-example', self.request._wuttaweb_registered_components)
+        self.assertEqual(self.request._wuttaweb_registered_components['foo-example'], 'FooExample')
+
+        # re-registering same name
+        self.request.register_component('foo-example', 'FooExample')
+        self.assertEqual(len(self.request._wuttaweb_registered_components), 1)
+        self.assertIn('foo-example', self.request._wuttaweb_registered_components)
+        self.assertEqual(self.request._wuttaweb_registered_components['foo-example'], 'FooExample')
+
     def test_get_referrer(self):
         event = MagicMock(request=self.request)
 
@@ -346,7 +374,7 @@ class TestBeforeRender(TestCase):
 
     def setUp(self):
         self.config = WuttaConfig(defaults={
-            'wutta.web.menus.handler_spec': 'tests.util:NullMenuHandler',
+            'wutta.web.menus.handler.spec': 'tests.util:NullMenuHandler',
         })
 
     def make_request(self):
@@ -378,6 +406,24 @@ class TestBeforeRender(TestCase):
         self.assertIn('json', event)
         self.assertIs(event['json'], json)
 
+        # current theme should be 'default' and picker not exposed
+        self.assertEqual(event['theme'], 'default')
+        self.assertFalse(event['expose_theme_picker'])
+        self.assertNotIn('available_themes', event)
+
+    def test_custom_theme(self):
+        self.config.setdefault('wuttaweb.themes.expose_picker', 'true')
+        request = self.make_request()
+        request.registry.settings['wuttaweb.theme'] = 'butterfly'
+        event = {'request': request}
+
+        # event dict will get populated with more context
+        subscribers.before_render(event)
+        self.assertEqual(event['theme'], 'butterfly')
+        self.assertTrue(event['expose_theme_picker'])
+        self.assertIn('available_themes', event)
+        self.assertEqual(event['available_themes'], ['default', 'butterfly'])
+
 
 class TestIncludeMe(TestCase):