point extensionapp's config dir at serverapp's config dir

Author: Zsailer

jupyter_server/extension/application.py

@@ -95,27 +95,20 @@ class method. This method can be set as a entry_point in
 
     # Name of the extension
     extension_name = Unicode(
-        "",
         help="Name of extension."
     )
 
-    @default("extension_name")
-    def _default_extension_name(self):
+    def _extension_name_default(self):
         try:
             return self.name
         except AttributeError:
             raise ValueError("The extension must be given a `name`.")
 
     INVALID_EXTENSION_NAME_CHARS = [' ', '.', '+', '/']
 
-    def _config_file_name_default(self):
-        """The default config file name."""
-        if not self.name:
-            return ''
-        return 'jupyter_{}_config'.format(self.extension_name.replace('-','_'))
-
-    def _validate_extension_name(self):
-        value = self.extension_name
+    @validate('extension_name')
+    def _validate_extension_name(self, value):
+        #value = self.extension_name
         if isinstance(value, str):
             # Validate that extension_name doesn't contain any invalid characters.
             for c in ExtensionApp.INVALID_EXTENSION_NAME_CHARS:
@@ -163,6 +156,22 @@ def static_url_prefix(self):
         help=_("""Handlers appended to the server.""")
     ).tag(config=True)
 
+    def _config_dir_default(self):
+        """Point the config directory at the server's config_dir by default."""
+        try:
+            return self.serverapp.config_dir
+        except AttributeError:
+            raise AttributeError(
+                "The ExtensionApp has not ServerApp "
+                "initialized. Try `.initialize_server()`."
+            )
+
+    def _config_file_name_default(self):
+        """The default config file name."""
+        if not self.extension_name:
+            return ''
+        return 'jupyter_{}_config'.format(self.extension_name.replace('-','_'))
+
     default_url = Unicode('/', config=True,
         help=_("The default URL to redirect to from `/`")
     )
@@ -217,7 +226,7 @@ def _prepare_config(self):
         """
         traits = self.class_own_traits().keys()
         self.extension_config = Config({t: getattr(self, t) for t in traits})
-        self.serverapp.web_app.settings['{}_config'.format(self.extension_name)] = self.extension_config
+        self.settings['{}_config'.format(self.extension_name)] = self.extension_config
 
     def _prepare_settings(self):
         # Make webapp settings accessible to initialize_settings method
@@ -304,10 +313,11 @@ def initialize(self, serverapp, argv=[]):
         - Passes settings to webapp
         - Appends handlers to webapp.
         """
-        self._validate_extension_name()
+        # Initialize ServerApp.
+        self.serverapp = serverapp
+        
         # Initialize the extension application
         super(ExtensionApp, self).initialize(argv=argv)
-        self.serverapp = serverapp
 
         # Initialize config, settings, templates, and handlers.
         self._prepare_config()

tests/extension/conftest.py

@@ -20,6 +20,13 @@ def initialize_handlers(self):
         self.handlers.append(('/mock', MockExtensionHandler))
 
 
+@pytest.fixture
+def config_file(config_dir):
+    f = config_dir.joinpath('jupyter_mock_config.py')
+    f.write_text("c.MockExtension.mock_trait ='config from file'")
+    return f
+
+
 @pytest.fixture
 def extended_serverapp(serverapp):
     m = MockExtension()

tests/extension/test_app.py

@@ -49,11 +49,18 @@ def test_instance_creation_with_instance_args(trait_name, trait_value):
 def test_instance_creation_with_argv(serverapp, trait_name, trait_value):
     kwarg = {}
     kwarg.setdefault(trait_name, trait_value)
-
     argv = [
         '--MockExtension.{name}={value}'.format(name=trait_name, value=trait_value)
     ]
-
     mock_extension = MockExtension()
     mock_extension.initialize(serverapp, argv=argv)
     assert getattr(mock_extension, trait_name) == trait_value
+
+
+def test_extensionapp_load_config_file(config_file, serverapp, extended_serverapp):
+    # Assert default config_file_paths is the same in the app and extension.
+    assert extended_serverapp.config_file_paths == serverapp.config_file_paths
+    assert extended_serverapp.config_file_name == 'jupyter_mock_config'
+    assert extended_serverapp.config_dir == serverapp.config_dir
+    # Assert that the trait is updated by config file
+    assert extended_serverapp.mock_trait == 'config from file'