OP#10323: Show no progressbar for a load requested outside any page

Loading an otconfig with track files over HTTP always failed: OTCloud hands
its UI Worker an otconfig through a plain endpoint, whose task carries no
NiceGUI slot, and NiceguiProgressbar.open() resolved context.client, which
raises on an empty slot stack. A missing page context now counts as having
no browser to show the dialog in, like the startup preload already did.

Author: randy-seng

OTAnalytics/plugin_ui/nicegui_gui/nicegui/progressbar.py

@@ -84,12 +84,10 @@ def is_open(self) -> bool:
     def open(self) -> None:
         """Build and show the progressbar dialog.
 
-        Does nothing without a browser to show it in, which is the case while
-        input files given on the command line are preloaded at startup, and
-        nothing when there is no progress left to show, because only progress
-        closes the dialog again.
+        Does nothing without a browser to show it in, and nothing when there is
+        no progress left to show, because only progress closes the dialog again.
         """
-        if context.client.is_auto_index_client or self._state.finished:
+        if not _has_browser_to_show_in() or self._state.finished:
             return
         with ui.dialog().props("persistent") as dialog, ui.card().classes("w-96"):
             self._dialog = dialog
@@ -202,3 +200,16 @@ def __call__(self, sequence: Sequence, description: str, unit: str) -> Iterable:
         return AutoIncrementingProgressbar(
             sequence, progressbar.counter, progressbar.notify, step_percentage=1
         )
+
+
+def _has_browser_to_show_in() -> bool:
+    """Whether the current task renders into a page a browser is looking at.
+
+    Two callers have none: preloading input files given on the command line at
+    startup, which runs in the auto-index client before any page is served, and
+    a load requested over HTTP rather than from a page, such as OTCloud handing
+    its UI Worker an otconfig, whose task has no NiceGUI slot at all.
+    """
+    if not context.slot_stack:
+        return False
+    return not context.client.is_auto_index_client

tests/unit/OTAnalytics/plugin_ui/nicegui_gui/nicegui/test_progressbar.py

@@ -1,5 +1,6 @@
 """Tests for the in-browser progressbar of the webui."""
 
+import asyncio
 from dataclasses import dataclass
 
 import pytest
@@ -240,6 +241,24 @@ async def test_shows_nothing_when_no_browser_is_connected(
 
         assert target.is_open is False
 
+    @pytest.mark.asyncio
+    async def test_shows_nothing_when_opened_outside_any_page(
+        self, user: User, resource_manager: ResourceManager
+    ) -> None:
+        """A load requested over HTTP, not from a page, has no browser to show in.
+
+        OTCloud hands the UI Worker an otconfig through a plain HTTP endpoint,
+        whose task carries no NiceGUI slot at all.
+
+        #Requirement https://openproject.platomo.de/wp/10281
+        """
+        given = create_given(resource_manager)
+        target = create_target(given, total=2)
+
+        await asyncio.create_task(open_outside_any_page(target))
+
+        assert target.is_open is False
+
     @pytest.mark.asyncio
     async def test_still_tracks_progress_when_no_browser_is_connected(
         self, user: User, resource_manager: ResourceManager
@@ -253,3 +272,8 @@ async def test_still_tracks_progress_when_no_browser_is_connected(
         target.complete("first.mp4")
 
         assert target.state.message == "Downloading 1 / 2 files"
+
+
+async def open_outside_any_page(progressbar: NiceguiProgressbar) -> None:
+    """Open the progressbar in a fresh task, whose NiceGUI slot stack is empty."""
+    progressbar.open()