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_util.py

@@ -11,9 +11,12 @@ from fanstatic import Library, Resource
 from pyramid import testing
 
 from wuttjamaican.conf import WuttaConfig
-from wuttjamaican.testing import ConfigTestCase
+from wuttjamaican.testing import ConfigTestCase, DataTestCase
+from wuttjamaican.util import resource_path
 
 from wuttaweb import util as mod
+from wuttaweb.app import establish_theme
+from wuttaweb.testing import WebTestCase
 
 
 class TestFieldList(TestCase):
@@ -621,3 +624,89 @@ class TestMakeJsonSafe(TestCase):
             'bar',
             "Betty Boop",
         ])
+
+
+class TestGetAvailableThemes(TestCase):
+
+    def setUp(self):
+        self.config = WuttaConfig()
+        self.app = self.config.get_app()
+
+    def test_defaults(self):
+        themes = mod.get_available_themes(self.config)
+        self.assertEqual(themes, ['default', 'butterfly'])
+
+    def test_sorting(self):
+        self.config.setdefault('wuttaweb.themes.keys', 'default, foo2, foo4, foo1')
+        themes = mod.get_available_themes(self.config)
+        self.assertEqual(themes, ['default', 'foo1', 'foo2', 'foo4'])
+
+    def test_default_omitted(self):
+        self.config.setdefault('wuttaweb.themes.keys', 'butterfly, foo')
+        themes = mod.get_available_themes(self.config)
+        self.assertEqual(themes, ['default', 'butterfly', 'foo'])
+
+    def test_default_notfirst(self):
+        self.config.setdefault('wuttaweb.themes.keys', 'butterfly, foo, default')
+        themes = mod.get_available_themes(self.config)
+        self.assertEqual(themes, ['default', 'butterfly', 'foo'])
+
+
+class TestGetEffectiveTheme(DataTestCase):
+
+    def test_default(self):
+        theme = mod.get_effective_theme(self.config)
+        self.assertEqual(theme, 'default')
+
+    def test_override_config(self):
+        self.app.save_setting(self.session, 'wuttaweb.theme', 'butterfly')
+        self.session.commit()
+        theme = mod.get_effective_theme(self.config)
+        self.assertEqual(theme, 'butterfly')
+
+    def test_override_param(self):
+        theme = mod.get_effective_theme(self.config, theme='butterfly')
+        self.assertEqual(theme, 'butterfly')
+
+    def test_invalid(self):
+        self.assertRaises(ValueError,  mod.get_effective_theme, self.config, theme='invalid')
+
+
+class TestThemeTemplatePath(DataTestCase):
+
+    def test_default(self):
+        path = mod.get_theme_template_path(self.config, theme='default')
+        # nb. even though the path does not exist, we still want to
+        # pretend like it does, hence prev call should return this:
+        expected = resource_path('wuttaweb:templates/themes/default')
+        self.assertEqual(path, expected)
+
+    def test_default(self):
+        path = mod.get_theme_template_path(self.config, theme='butterfly')
+        expected = resource_path('wuttaweb:templates/themes/butterfly')
+        self.assertEqual(path, expected)
+
+    def test_custom(self):
+        self.config.setdefault('wuttaweb.themes.keys', 'default, butterfly, poser')
+        self.config.setdefault('wuttaweb.theme.poser', '/tmp/poser-theme')
+        path = mod.get_theme_template_path(self.config, theme='poser')
+        self.assertEqual(path, '/tmp/poser-theme')
+
+
+class TestSetAppTheme(WebTestCase):
+
+    def test_basic(self):
+
+        # establish default
+        settings = self.request.registry.settings
+        self.assertNotIn('wuttaweb.theme', settings)
+        establish_theme(settings)
+        self.assertEqual(settings['wuttaweb.theme'], 'default')
+
+        # set to butterfly
+        mod.set_app_theme(self.request, 'butterfly', session=self.session)
+        self.assertEqual(settings['wuttaweb.theme'], 'butterfly')
+
+        # set back to default
+        mod.set_app_theme(self.request, 'default', session=self.session)
+        self.assertEqual(settings['wuttaweb.theme'], 'default')