sdk-ui: add PinnedEventsLoaderError::TimelineReloadFailed.

This error will be returned when the room has pinned event ids but the timeline couldn't load any of them.

Also fix tests.

crates/matrix-sdk-ui/src/timeline/pinned_events_loader.rs

@@ -51,6 +51,7 @@ impl PinnedEventsLoader {
             .rev()
             .collect();
 
+        let has_pinned_event_ids = !pinned_event_ids.is_empty();
         let mut loaded_events = Vec::new();
         let mut event_ids_to_request = Vec::new();
         for ev_id in pinned_event_ids {
@@ -89,11 +90,15 @@ impl PinnedEventsLoader {
 
             for handle in handles {
                 if let Ok(Ok(ev)) = handle.await {
-                    loaded_events.push(ev)
+                    loaded_events.push(ev);
                 }
             }
         }
 
+        if has_pinned_event_ids && loaded_events.is_empty() {
+            return Err(PinnedEventsLoaderError::TimelineReloadFailed);
+        }
+
         info!("Saving {} pinned events to the cache", loaded_events.len());
         cache.set_bulk(&loaded_events).await;
 
@@ -198,4 +203,7 @@ pub enum PinnedEventsLoaderError {
 
     #[error("Timeline focus is not pinned events.")]
     TimelineFocusNotPinnedEvents,
+
+    #[error("Could not load pinned events.")]
+    TimelineReloadFailed,
 }

crates/matrix-sdk-ui/tests/integration/timeline/pinned_event.rs

@@ -166,21 +166,15 @@ async fn test_max_events_to_load_is_honored() {
         .await;
 
     let room = test_helper.client.get_room(&room_id).unwrap();
-    let timeline = Timeline::builder(&room)
+    let ret = Timeline::builder(&room)
         .with_focus(TimelineFocus::PinnedEvents { max_events_to_load: 1 })
         .build()
-        .await
-        .unwrap();
-
-    assert!(
-        timeline.live_back_pagination_status().await.is_none(),
-        "there should be no live back-pagination status for a focused timeline"
-    );
+        .await;
 
-    let (items, mut timeline_stream) = timeline.subscribe().await;
+    // We're only taking the last event id, `$2`, and it's not available so the
+    // timeline fails to initialise.
+    assert!(ret.is_err());
 
-    assert!(items.is_empty()); // We're only taking the last event id, `$2`, and it's not available
-    assert_pending!(timeline_stream);
     test_helper.server.reset().await;
 }
 
@@ -256,15 +250,68 @@ async fn test_cached_events_are_kept_for_different_room_instances() {
     let room = test_helper.client.get_room(&room_id).unwrap();
 
     // And a new timeline one
-    let timeline = Timeline::builder(&room)
+    let ret = Timeline::builder(&room)
         .with_focus(TimelineFocus::PinnedEvents { max_events_to_load: 2 })
         .build()
+        .await;
+
+    // Since the events are no longer in the cache the timeline couldn't load them
+    // and can't be initialised.
+    assert!(ret.is_err());
+
+    test_helper.server.reset().await;
+}
+
+#[async_test]
+async fn test_pinned_timeline_with_pinned_event_ids_and_empty_result_fails() {
+    let mut test_helper = TestHelper::new().await;
+    let room_id = test_helper.room_id.clone();
+
+    // Join the room
+    let _ = test_helper.setup_initial_sync_response().await;
+    test_helper.server.reset().await;
+
+    // Load initial timeline items: a `m.room.pinned_events` with event $1 and $2
+    // pinned, but they're not available neither in the cache nor in the HS
+    let _ = test_helper.setup_sync_response(Vec::new(), Some(vec!["$1", "$2"])).await;
+
+    let room = test_helper.client.get_room(&room_id).unwrap();
+    let ret = Timeline::builder(&room)
+        .with_focus(TimelineFocus::PinnedEvents { max_events_to_load: 1 })
+        .build()
+        .await;
+
+    // The timeline couldn't load any events so it fails to initialise
+    assert!(ret.is_err());
+
+    test_helper.server.reset().await;
+}
+
+#[async_test]
+async fn test_pinned_timeline_with_no_pinned_event_ids_is_just_empty() {
+    let mut test_helper = TestHelper::new().await;
+    let room_id = test_helper.room_id.clone();
+
+    // Join the room
+    let _ = test_helper.setup_initial_sync_response().await;
+    test_helper.server.reset().await;
+
+    // Load initial timeline items: an empty `m.room.pinned_events` event
+    let _ = test_helper.setup_sync_response(Vec::new(), Some(Vec::new())).await;
+
+    let room = test_helper.client.get_room(&room_id).unwrap();
+    let timeline = Timeline::builder(&room)
+        .with_focus(TimelineFocus::PinnedEvents { max_events_to_load: 1 })
+        .build()
         .await
         .unwrap();
 
+    // The timeline couldn't load any events, but it expected none, so it just
+    // returns an empty list
     let (items, _) = timeline.subscribe().await;
-    assert!(items.is_empty()); // These events are no longer in the cache, so
-                               // they couldn't be retrieved
+    assert!(items.is_empty());
+
+    test_helper.server.reset().await;
 }
 
 struct TestHelper {