Fix linked chunk update when next chunk is not there

Author: ospfranco

crates/matrix-sdk-indexeddb/src/event_cache_store/mod.rs

@@ -1460,4 +1460,37 @@ mod tests {
             });
         }
     }
+
+    #[async_test]
+    async fn test_linked_chunk_new_gap_chunk() {
+        let store = get_event_cache_store().await.expect("creating cache store failed");
+
+        let room_id = &DEFAULT_TEST_ROOM_ID;
+
+        store
+            .handle_linked_chunk_updates(
+                room_id,
+                vec![Update::NewGapChunk {
+                    previous: None,
+                    new: ChunkIdentifier::new(42),
+                    next: None,
+                    gap: Gap { prev_token: "raclette".to_owned() },
+                }],
+            )
+            .await
+            .unwrap();
+
+        let mut chunks = store.reload_linked_chunk(room_id).await.unwrap();
+
+        assert_eq!(chunks.len(), 1);
+
+        // Chunks are ordered from smaller to bigger IDs.
+        let c = chunks.remove(0);
+        assert_eq!(c.identifier, ChunkIdentifier::new(42));
+        assert_eq!(c.previous, None);
+        assert_eq!(c.next, None);
+        assert_matches!(c.content, ChunkContent::Gap(gap) => {
+            assert_eq!(gap.prev_token, "raclette");
+        });
+    }
 }