fix: traitlets5 compatibility

tests/app/config_paths_test.py

@@ -10,7 +10,7 @@
 @pytest.fixture
 def voila_config_file_paths_arg():
     path = os.path.join(BASE_DIR, '..', 'configs', 'general')
-    return '--VoilaTest.config_file_paths=[%r]' % path
+    return '--VoilaTest.config_file_paths=%s' % path
 
 
 def test_config_app(voila_app):

tests/app/template_cli_test.py

@@ -10,10 +10,10 @@
 def voila_args_extra():
     path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/'))
     path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default'))
-    return ['--template=None', '--VoilaTest.template_paths=[%r, %r]' % (path_test_template, path_default), '--VoilaExecutor.timeout=240']
+    return ['--template=\'\'', '--VoilaTest.template_paths=%s' % path_test_template, '--VoilaTest.template_paths=%s' % path_default, '--VoilaExecutor.timeout=240']
 
 
-async def test_template_test(http_server_client, base_url):
+async def test_template_test(voila_app, http_server_client, base_url):
     response = await http_server_client.fetch(base_url)
     assert response.code == 200
     assert 'test_template.css' in response.body.decode('utf-8')

voila/app.py

@@ -338,7 +338,8 @@ def initialize(self, argv=None):
         signal.signal(signal.SIGTERM, self._handle_signal_stop)
 
     def setup_template_dirs(self):
-        if self.voila_configuration.template:
+        # TODO: with traitlets 5 we cannot assign a Falsy anymore, '' is a workaround for now
+        if self.voila_configuration.template and self.voila_configuration.template != "''":
             template_name = self.voila_configuration.template
             self.template_paths = collect_template_paths(['voila', 'nbconvert'], template_name, prune=True)
             self.static_paths = collect_static_paths(['voila', 'nbconvert'], template_name)