Validate preferred_dir relative to root_dir location, update tests

jupyter_server/services/contents/manager.py

@@ -83,6 +83,14 @@ def emit(self, data):
         ),
     )
 
+    @validate("preferred_dir")
+    def _validate_preferred_dir(self, proposal):
+        value = proposal["value"]
+
+        if not value.startswith(self.root_dir):
+            raise TraitError(_i18n(f"{value} is outside root contents directory"))
+        return value
+
     allow_hidden = Bool(False, config=True, help="Allow access to hidden files")
 
     notary = Instance(sign.NotebookNotary)

tests/test_serverapp.py

@@ -386,9 +386,8 @@ async def test_invalid_preferred_dir_not_root_subdir_set(tmp_path, jp_configurab
     not_subdir_path = os.path.relpath(tmp_path, path)
 
     app = jp_configurable_serverapp(root_dir=path)
-    app.contents_manager.preferred_dir = not_subdir_path
-    with pytest.raises(HTTPError) as error:
-        await app.contents_manager.dir_exists(app.contents_manager.preferred_dir)
+    with pytest.raises(TraitError) as error:
+        app.contents_manager.preferred_dir = not_subdir_path
 
     assert "is outside root contents directory" in str(error.value)
 
@@ -399,12 +398,7 @@ async def test_absolute_preferred_dir_not_root_subdir_set(tmp_path, jp_configura
     not_subdir_path = str(tmp_path)
 
     app = jp_configurable_serverapp(root_dir=path)
-    app.contents_manager.preferred_dir = not_subdir_path
-    with pytest.raises(HTTPError) as error:
-        print(app.contents_manager.preferred_dir)
-        await app.contents_manager.dir_exists(app.contents_manager.preferred_dir)
+    with pytest.raises(TraitError) as error:
+        app.contents_manager.preferred_dir = not_subdir_path
 
-    if os.name == "nt":
-        assert "is not a relative API path" in str(error.value)
-    else:
-        assert "Preferred directory not found" in str(error.value)
+    assert "is outside root contents directory" in str(error.value)