Ensure resources are bundled correctly in Jupyter server extension (#…

…4133)

* Ensure resources are bundled correctly in Jupyter server extension

* Add test

panel/io/jupyter_server_extension.py

@@ -274,15 +274,16 @@ def render(self) -> HTML:
         Renders the application to an IPython.display.HTML object to
         be served by the `PanelJupyterHandler`.
         """
-        res = HTML(server_html_page_for_session(
-            self.session,
-            resources=self.resources,
-            title=self.session.document.title,
-            template=self.session.document.template,
-            template_variables=self.session.document.template_variables
-        ))
+        with set_curdoc(self.session.document):
+            html = server_html_page_for_session(
+                self.session,
+                resources=self.resources,
+                title=self.session.document.title,
+                template=self.session.document.template,
+                template_variables=self.session.document.template_variables
+            )
         publish_display_data({'application/bokeh-extensions': extension_dirs})
-        return res
+        return HTML(html)
 
 
 class PanelJupyterHandler(JupyterHandler):

panel/tests/ui/io/app.py

@@ -1,5 +1,7 @@
 import panel as pn
 
+pn.config.raw_css = ['.bk.string { color: purple }']
+
 button = pn.widgets.Button(name='Click')
 
 string = pn.pane.Str(object=0, css_classes=['string'])

panel/tests/ui/io/test_jupyter_server_extension.py

@@ -23,6 +23,14 @@ def test_jupyter_server(page, jupyter_preview):
 
     wait_until(lambda: page.text_content('.bk.string') == '2', page)
 
+@not_windows
+@pytest.mark.flaky(max_runs=3)
+def test_jupyter_server_custom_resources(page, jupyter_preview):
+    page.goto(f"{jupyter_preview}/app.py", timeout=30000)
+
+    assert page.locator('.bk.string').evaluate("""(element) =>
+        window.getComputedStyle(element).getPropertyValue('color')""") == 'rgb(128, 0, 128)'
+
 @not_windows
 @pytest.mark.flaky(max_runs=3)
 def test_jupyter_server_kernel_error(page, jupyter_preview):