Use placeholder user models in ranked play if online lookups fail (ppy#37455)

Suboptimal? Sure. But the primary goal is not to crash. Crashing is a
failure of the game programmer.

Better can be done later.

Remedies/fixes ppy#37421.

Author: Bartłomiej Dach

osu.Game.Tests/Visual/RankedPlay/TestSceneRankedPlayScreen.cs

@@ -26,21 +26,35 @@ public override void SetUpSteps()
 
             AddStep("join room", () => JoinRoom(CreateDefaultRoom(MatchType.RankedPlay)));
             WaitForJoined();
+        }
 
+        [Test]
+        public void TestIntroStage()
+        {
             AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
 
             AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
+            AddStep("set round warmup phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.RoundWarmup, s => s.StarRating = 6.3f).WaitSafely());
         }
 
         [Test]
-        public void TestIntroStage()
+        public void TestUnresolvedUser()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = TestUserLookupCache.UNRESOLVED_USER_ID }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set round warmup phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.RoundWarmup, s => s.StarRating = 6.3f).WaitSafely());
         }
 
         [Test]
         public void TestDiscardCardsStage()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set discard phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardDiscard).WaitSafely());
 
             AddWaitStep("wait", 3);
@@ -72,6 +86,10 @@ public void TestDiscardCardsStage()
         [Test]
         public void TestAddRemoveCards()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set discard phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardDiscard).WaitSafely());
 
             for (int i = 0; i < 3; i++)
@@ -84,6 +102,10 @@ public void TestAddRemoveCards()
         [Test]
         public void TestRevealCards()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             var requestHandler = new BeatmapRequestHandler();
 
             AddStep("setup request handler", () => ((DummyAPIAccess)API).HandleRequest = requestHandler.HandleRequest);
@@ -104,6 +126,10 @@ public void TestRevealCards()
         [Test]
         public void TestPlayCardDirect()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set play phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardPlay, state => state.ActiveUserId = API.LocalUser.Value.OnlineID).WaitSafely());
             AddWaitStep("wait", 3);
             AddStep("play card", () => MultiplayerClient.PlayCard(hand => hand[0]).WaitSafely());
@@ -112,6 +138,10 @@ public void TestPlayCardDirect()
         [Test]
         public void TestDiscardCardsDirect()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set discard phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardDiscard).WaitSafely());
             AddWaitStep("wait", 3);
             AddStep("discard cards", () => MultiplayerClient.DiscardCards(hand => hand.Take(3)).WaitSafely());
@@ -122,6 +152,10 @@ public void TestDiscardCardsDirect()
         [Test]
         public void TestPlayStage()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set play phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardPlay, state => state.ActiveUserId = API.LocalUser.Value.OnlineID).WaitSafely());
             AddUntilStep("wait until cards are present", () => this.ChildrenOfType<PlayerHandOfCards.PlayerHandCard>().Count() == 5);
 
@@ -153,6 +187,10 @@ public void TestPlayStage()
         [Test]
         public void TestOtherPlaysCard()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set play phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardPlay, state => state.ActiveUserId = 2).WaitSafely());
             AddWaitStep("wait", 5);
             AddStep("play beatmap", () => MultiplayerClient.PlayUserCard(2, hand => hand[0]).WaitSafely());
@@ -166,6 +204,10 @@ public void TestOtherPlaysCard()
         [Test]
         public void TestHealthChange()
         {
+            AddStep("join other user", () => MultiplayerClient.AddUser(new APIUser { Id = 2 }));
+
+            AddStep("load screen", () => LoadScreen(screen = new RankedPlayScreen(MultiplayerClient.ClientRoom!)));
+
             AddStep("set play phase", () => MultiplayerClient.RankedPlayChangeStage(RankedPlayStage.CardPlay, state => state.ActiveUserId = 2).WaitSafely());
             AddWaitStep("wait", 5);
             AddStep("change player 1 health", () => MultiplayerClient.RankedPlayChangeUserState(MultiplayerClient.LocalUser!.UserID, state => state.Life = 250_000).WaitSafely());

osu.Game/Online/API/Requests/Responses/APIUser.cs

@@ -312,6 +312,12 @@ private APIRankHistory rankHistory
             Colour = @"9c0101",
         };
 
+        public static APIUser UnknownUser(int userId) => new APIUser
+        {
+            Id = userId,
+            Username = "Unknown user",
+        };
+
         public int OnlineID => Id;
 
         public bool Equals(APIUser other) => this.MatchesOnlineID(other);

osu.Game/Screens/OnlinePlay/Matchmaking/RankedPlay/Intro/IntroScreen.cs

@@ -60,8 +60,10 @@ private async Task loadUsers()
 
             var users = await userLookupCache.GetUsersAsync(userIds).ConfigureAwait(false);
 
-            var player = users.OfType<APIUser>().First(it => it.Id == api.LocalUser.Value.Id);
-            var opponent = users.OfType<APIUser>().First(it => it.Id != api.LocalUser.Value.Id);
+            var player = users.OfType<APIUser>().FirstOrDefault(it => it.Id == api.LocalUser.Value.Id)
+                         ?? api.LocalUser.Value;
+            var opponent = users.OfType<APIUser>().FirstOrDefault(it => it.Id != api.LocalUser.Value.Id)
+                           ?? APIUser.UnknownUser(userIds.First(id => id != api.LocalUser.Value.Id));
 
             int playerRating = roomState.Users[player.Id].Rating;
             int opponentRating = roomState.Users[opponent.Id].Rating;

osu.Game/Screens/OnlinePlay/Matchmaking/RankedPlay/RankedPlayScreen.cs

@@ -193,8 +193,8 @@ protected override void LoadComplete()
             int localUserId = api.LocalUser.Value.OnlineID;
             int opponentUserId = ((RankedPlayRoomState)client.Room!.MatchState!).Users.Keys.Single(it => it != localUserId);
 
-            localUser = users.GetUserAsync(localUserId).GetResultSafely()!;
-            opponentUser = users.GetUserAsync(opponentUserId).GetResultSafely()!;
+            localUser = users.GetUserAsync(localUserId).GetResultSafely() ?? api.LocalUser.Value;
+            opponentUser = users.GetUserAsync(opponentUserId).GetResultSafely() ?? APIUser.UnknownUser(opponentUserId);
 
             AddRangeInternal([
                 new RankedPlayCornerPiece(RankedPlayColourScheme.BLUE, Anchor.BottomLeft)

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

@@ -607,7 +607,7 @@ private void onMatchEvent(MatchServerEvent ev)
             switch (ev)
             {
                 case RollEvent rollEvent:
-                    var user = client.Room?.Users.SingleOrDefault(u => u.UserID == rollEvent.UserID)?.User ?? new APIUser { Username = "Unknown user" };
+                    var user = client.Room?.Users.SingleOrDefault(u => u.UserID == rollEvent.UserID)?.User ?? APIUser.UnknownUser(rollEvent.UserID);
                     string text = $"{user.Username} rolled {"point".ToQuantity(rollEvent.Result)} out of {rollEvent.Max}.";
                     chat.Channel.Value?.AddNewMessages(new InfoMessage(text));
                     break;

osu.Game/Screens/Play/Leaderboards/MultiplayerLeaderboardProvider.cs

@@ -89,11 +89,7 @@ private void load(OsuConfigManager config, IAPIProvider api, CancellationToken c
 
                                    for (int i = 0; i < lookedUpUsers.Length; i++)
                                    {
-                                       var user = lookedUpUsers[i] ?? new APIUser
-                                       {
-                                           Id = users[i].UserID,
-                                           Username = "Unknown user",
-                                       };
+                                       var user = lookedUpUsers[i] ?? APIUser.UnknownUser(users[i].UserID);
 
                                        var trackedUser = UserScores[user.Id];