Merge branch 'fix-spectator-restart-crash' into spectator-state-rework

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiplayer.cs

@@ -871,6 +871,53 @@ namespace osu.Game.Tests.Visual.Multiplayer
             AddUntilStep("queue is empty", () => this.ChildrenOfType<MultiplayerQueueList>().Single().Items.Count == 0);
         }
 
+        [Test]
+        public void TestGameplayStartsWhileInSpectatorScreen()
+        {
+            createRoom(() => new Room
+            {
+                Name = { Value = "Test Room" },
+                Playlist =
+                {
+                    new PlaylistItem
+                    {
+                        Beatmap = { Value = beatmaps.GetWorkingBeatmap(importedSet.Beatmaps.First(b => b.Ruleset.OnlineID == 0)).BeatmapInfo },
+                        Ruleset = { Value = new OsuRuleset().RulesetInfo },
+                    }
+                }
+            });
+
+            AddStep("join other user and make host", () =>
+            {
+                client.AddUser(new APIUser { Id = 1234 });
+                client.TransferHost(1234);
+            });
+
+            AddStep("set local user spectating", () => client.ChangeUserState(API.LocalUser.Value.OnlineID, MultiplayerUserState.Spectating));
+            AddUntilStep("wait for spectating state", () => client.LocalUser?.State == MultiplayerUserState.Spectating);
+
+            runGameplay();
+
+            AddStep("exit gameplay for other user", () => client.ChangeUserState(1234, MultiplayerUserState.Idle));
+            AddUntilStep("wait for room to be idle", () => client.Room?.State == MultiplayerRoomState.Open);
+
+            runGameplay();
+
+            void runGameplay()
+            {
+                AddStep("start match by other user", () =>
+                {
+                    client.ChangeUserState(1234, MultiplayerUserState.Ready);
+                    client.StartMatch();
+                });
+
+                AddUntilStep("wait for loading", () => client.Room?.State == MultiplayerRoomState.WaitingForLoad);
+                AddStep("set player loaded", () => client.ChangeUserState(1234, MultiplayerUserState.Loaded));
+                AddUntilStep("wait for gameplay to start", () => client.Room?.State == MultiplayerRoomState.Playing);
+                AddUntilStep("wait for local user to enter spectator", () => multiplayerComponents.CurrentScreen is MultiSpectatorScreen);
+            }
+        }
+
         private void enterGameplay()
         {
             pressReadyButton();

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSubScreen.cs

@@ -457,6 +457,13 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
                 return;
             }
 
+            // The beatmap is queried asynchronously when the selected item changes.
+            // This is an issue with MultiSpectatorScreen which is effectively in an always "ready" state and receives LoadRequested() callbacks
+            // even when it is not truly ready (i.e. the beatmap hasn't been selected by the client yet). For the time being, a simple fix to this is to ignore the callback.
+            // Note that spectator will be entered automatically when the client is capable of doing so via beatmap availability callbacks (see: updateBeatmapAvailability()).
+            if (client.LocalUser?.State == MultiplayerUserState.Spectating && (SelectedItem.Value == null || Beatmap.IsDefault))
+                return;
+
             StartPlay();
 
             readyClickOperation?.Dispose();