Introduce concept of HitObjectParsers, fix tests and stop using reflection (unreliable due to lazy loading).

osu.Game/Beatmaps/Formats/BeatmapDecoder.cs

@@ -48,6 +48,8 @@ namespace osu.Game.Beatmaps.Formats
                 new Color4(121,9,13, 255),
             };
 
+            if (colours.Count == 0) return;
+
             int i = -1;
 
             foreach (HitObject h in b.HitObjects)

osu.Game/Beatmaps/Formats/OsuLegacyDecoder.cs

@@ -221,7 +221,9 @@ namespace osu.Game.Beatmaps.Formats
                     BaseDifficulty = new BaseDifficulty(),
                 },
             };
-            
+
+            HitObjectParser parser = null;
+
             var section = Section.None;
             string line;
             while (true)
@@ -233,14 +235,14 @@ namespace osu.Game.Beatmaps.Formats
                     continue;
                 if (line.StartsWith(@"osu file format v"))
                     continue;
-                    
+
                 if (line.StartsWith(@"[") && line.EndsWith(@"]"))
                 {
                     if (!Enum.TryParse(line.Substring(1, line.Length - 2), out section))
                         throw new InvalidDataException($@"Unknown osu section {line}");
                     continue;
                 }
-                
+
                 string val = line, key = null;
                 if (section != Section.Events && section != Section.TimingPoints && section != Section.HitObjects)
                 {
@@ -251,6 +253,7 @@ namespace osu.Game.Beatmaps.Formats
                 {
                     case Section.General:
                         handleGeneral(beatmap, key, val);
+                        parser = Ruleset.GetRuleset(beatmap.BeatmapInfo.Mode).CreateHitObjectParser();
                         break;
                     case Section.Editor:
                         handleEditor(beatmap, key, val);
@@ -271,13 +274,13 @@ namespace osu.Game.Beatmaps.Formats
                         handleColours(beatmap, key, val);
                         break;
                     case Section.HitObjects:
-                        var h = HitObject.Parse(beatmap.BeatmapInfo.Mode, val);
-                        if (h != null)
-                            beatmap.HitObjects.Add(h);
+                        var obj = parser?.Parse(val);
+                        if (obj != null)
+                            beatmap.HitObjects.Add(obj);
                         break;
                 }
             }
-            
+
             return beatmap;
         }
     }

osu.Game/Modes/Objects/HitObject.cs

@@ -21,17 +21,5 @@ namespace osu.Game.Modes.Objects
         public double Duration => EndTime - StartTime;
 
         public HitSampleInfo Sample;
-
-        public static HitObject Parse(PlayMode mode, string val)
-        {
-            //TODO: move to modular HitObjectParser system rather than static parsing. (https://github.com/ppy/osu/pull/60/files#r83135780)
-            switch (mode)
-            {
-                case PlayMode.Osu:
-                    return null; //return OsuBaseHit.Parse(val);
-                default:
-                    return null;
-            }
-        }
     }
 }

osu.Game/Modes/Objects/HitObjectParser.cs

@@ -0,0 +1,16 @@
+//Copyright (c) 2007-2016 ppy Pty Ltd <contact@ppy.sh>.
+//Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace osu.Game.Modes.Objects
+{
+    public abstract class HitObjectParser
+    {
+        public abstract HitObject Parse(string text);
+    }
+}

osu.Game/Modes/Ruleset.cs

@@ -13,17 +13,19 @@ namespace osu.Game.Modes
 {
     public abstract class Ruleset
     {
+        private static List<Type> availableRulesets = new List<Type>();
+
         public abstract ScoreOverlay CreateScoreOverlay();
 
         public abstract HitRenderer CreateHitRendererWith(List<HitObject> objects);
 
+        public abstract HitObjectParser CreateHitObjectParser();
+
+        public static void Register(Ruleset ruleset) => availableRulesets.Add(ruleset.GetType());
+
         public static Ruleset GetRuleset(PlayMode mode)
         {
-            Type type = AppDomain.CurrentDomain
-                                .GetAssemblies()
-                                .Where(a => a.FullName.Contains($@"osu.Game.Modes.{mode}"))
-                                .SelectMany(a => a.GetTypes())
-                                .FirstOrDefault(t => t.Name == $@"{mode}Ruleset");
+            Type type = availableRulesets.FirstOrDefault(t => t.Name == $@"{mode}Ruleset");
 
             if (type == null)
                 return null;

osu.Game/osu.Game.csproj

@@ -63,6 +63,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Modes\Objects\HitObjectParser.cs" />
     <Compile Include="Overlays\DragBar.cs" />
     <Compile Include="Overlays\MusicController.cs" />
     <Compile Include="Beatmaps\Beatmap.cs" />