[F&O] 修复一些小问题，补充测试等

Author: Starrah

tests/chu/ChuTests.cs

@@ -1,6 +1,5 @@
+using System.Reflection;
 using MuConvert.chu;
-using MuConvert.parser;
-using MuConvert.utils;
 
 namespace MuConvert.Tests.chu;
 
@@ -28,7 +27,67 @@ public void C2sRoundTrip()
         var (chart, _) = new C2sParser().Parse(File.ReadAllText(C2sPath));
         var (rt, _) = new C2sGenerator().Generate(chart);
         var (reparsed, _) = new C2sParser().Parse(rt);
+
         Assert.Equal(chart.Notes.Count, reparsed.Notes.Count);
+
+        var originalSnapshots = chart.Notes
+            .Select(SnapshotNote)
+            .OrderBy(s => s)
+            .ToArray();
+
+        var reparsedSnapshots = reparsed.Notes
+            .Select(SnapshotNote)
+            .OrderBy(s => s)
+            .ToArray();
+
+        Assert.Equal(originalSnapshots, reparsedSnapshots);
+    }
+
+    /// <summary>
+    /// Builds a stable, comparable string from a note's public instance properties (name-sorted)
+    /// so round-trip tests verify no field loss without hard-coding each property in the test.
+    /// </summary>
+    private static string SnapshotNote(ChuNote note)
+    {
+        var props = typeof(ChuNote).GetProperties(BindingFlags.Instance | BindingFlags.Public);
+        var parts = props
+            .OrderBy(p => p.Name)
+            .Select(p => $"{p.Name}={p.GetValue(note)}");
+        return string.Join("|", parts);
+    }
+
+    /// <summary>
+    /// Same tick scaling as <see cref="C2sGenerator"/> when converting UGC → C2S (384 ticks per measure).
+    /// </summary>
+    private static ChuNote UgcNoteScaledToC2sTicks(ChuNote n, int ticksPerBeat)
+    {
+        const int c2sResolution = 384;
+        int scaleDown(int v) => (int)((long)v * (c2sResolution / 4) / ticksPerBeat);
+        return new ChuNote
+        {
+            Type = n.Type, Measure = n.Measure, Offset = scaleDown(n.Offset),
+            Cell = n.Cell, Width = n.Width,
+            HoldDuration = scaleDown(n.HoldDuration), SlideDuration = scaleDown(n.SlideDuration),
+            EndCell = n.EndCell, EndWidth = n.EndWidth,
+            Extra = n.Extra, TargetNote = n.TargetNote, AirHoldDuration = scaleDown(n.AirHoldDuration),
+            StartHeight = n.StartHeight, TargetHeight = n.TargetHeight, NoteColor = n.NoteColor,
+        };
+    }
+
+    /// <summary>
+    /// Compares UGC-side notes to C2S-side notes in C2S tick space (384): snapshots of
+    /// <see cref="UgcNoteScaledToC2sTicks"/> for each <paramref name="ugc"/> note vs snapshots of <paramref name="c2s"/> notes.
+    /// Use with <c>UgcToC2sViaGenerator</c> (source UGC, C2S from generate+parse) or <c>C2sToUgcViaGenerator</c> (UGC from generate+parse, source C2S).
+    /// </summary>
+    private static void AssertUgcNotesEquivalentToReparsedC2s(UgcChart ugc, C2sChart c2s, bool isUgcReference)
+    {
+        var ugcSnaps = ugc.Notes
+            .Select(n => SnapshotNote(UgcNoteScaledToC2sTicks(n, ugc.TicksPerBeat)))
+            .OrderBy(s => s)
+            .ToArray();
+        var c2sSnaps = c2s.Notes.Select(SnapshotNote).OrderBy(s => s).ToArray();
+        if (isUgcReference) Assert.Equal(ugcSnaps, c2sSnaps);
+        else Assert.Equal(c2sSnaps, ugcSnaps);
     }
 
     [Fact]
@@ -45,18 +104,32 @@ public void UgcToC2sViaGenerator()
     {
         if (!File.Exists(UgcPath)) throw new SkipException($"Missing: {UgcPath}");
         var (ugc, _) = new UgcParser().Parse(File.ReadAllText(UgcPath));
+        Assert.NotEmpty(ugc.Notes);
+
         var (c2sText, _) = new C2sGenerator().Generate(ugc);
         Assert.Contains("VERSION", c2sText);
         Assert.Contains("TAP\t", c2sText);
+
+        // 再把转出来的c2s，parse回去，比较是否和一开始的ugc等价（注意不是文本 round-trip，而是 IR 等价，允许字段重排但不允许信息丢失）
+        var (c2sChart, _) = new C2sParser().Parse(c2sText);
+        Assert.NotEmpty(c2sChart.Notes);
+        AssertUgcNotesEquivalentToReparsedC2s(ugc, c2sChart, true);
     }
 
     [Fact]
     public void C2sToUgcViaGenerator()
     {
         if (!File.Exists(C2sPath)) throw new SkipException($"Missing: {C2sPath}");
         var (c2s, _) = new C2sParser().Parse(File.ReadAllText(C2sPath));
+        Assert.NotEmpty(c2s.Notes);
+        
         var (ugcText, _) = new UgcGenerator().Generate(c2s);
         Assert.Contains("@VER", ugcText);
         Assert.Contains("#5'0", ugcText);
+
+        // 再把转出来的ugc，parse回去，比较是否和一开始的c2s等价
+        var (ugcReparsed, _) = new UgcParser().Parse(ugcText);
+        Assert.NotEmpty(ugcReparsed.Notes);
+        AssertUgcNotesEquivalentToReparsedC2s(ugcReparsed, c2s, false);
     }
 }