Follow the official PR to create the mod test scene.

But scoring is not implemented, so mark the test scene ignore.

see:
https://github.com/ppy/osu/pull/26036/files

osu.Game.Rulesets.Karaoke.Tests/Mods/TestSceneKaraokeModSuddenDeath.cs

@@ -0,0 +1,77 @@
+// Copyright (c) andy840119 <[email protected]>. Licensed under the GPL Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using NUnit.Framework;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets.Karaoke.Mods;
+using osu.Game.Rulesets.Karaoke.Objects;
+using osu.Game.Rulesets.Karaoke.Replays;
+using osu.Game.Rulesets.Karaoke.Tests.Helper;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Replays;
+using osu.Game.Tests.Visual;
+
+namespace osu.Game.Rulesets.Karaoke.Tests.Mods;
+
+[Ignore("Scoring is not implemented.")]
+public partial class TestSceneKaraokeModSuddenDeath : ModFailConditionTestScene
+{
+    protected override Ruleset CreatePlayerRuleset() => new KaraokeRuleset();
+
+    private readonly Lyric referencedLyric = TestCaseNoteHelper.CreateLyricForNote(1, "カラオケ", 1000, 1000);
+
+    public TestSceneKaraokeModSuddenDeath()
+        : base(new KaraokeModSuddenDeath())
+    {
+    }
+
+    [Test]
+    public void TestGreatHit() => CreateModTest(new ModTestData
+    {
+        Mod = new KaraokeModSuddenDeath(),
+        PassCondition = () => ((ModFailConditionTestPlayer)Player).CheckFailed(false),
+        Autoplay = false,
+        Beatmap = new Beatmap
+        {
+            HitObjects = new List<HitObject>
+            {
+                referencedLyric,
+                new Note
+                {
+                    ReferenceLyricId = referencedLyric.ID,
+                    Tone = new Tone(0),
+                },
+            },
+        },
+        ReplayFrames = new List<ReplayFrame>
+        {
+            new KaraokeReplayFrame(1000, 0),
+            new KaraokeReplayFrame(2000, 0),
+        },
+    });
+
+    [Test]
+    public void TestBreakOnHoldNote() => CreateModTest(new ModTestData
+    {
+        Mod = new KaraokeModSuddenDeath(),
+        PassCondition = () => ((ModFailConditionTestPlayer)Player).CheckFailed(true) && Player.Results.Count == 2,
+        Autoplay = false,
+        Beatmap = new Beatmap
+        {
+            HitObjects = new List<HitObject>
+            {
+                referencedLyric,
+                new Note
+                {
+                    ReferenceLyricId = referencedLyric.ID,
+                    Tone = new Tone(0),
+                },
+            },
+        },
+        ReplayFrames = new List<ReplayFrame>
+        {
+            new KaraokeReplayFrame(0, -1),
+        },
+    });
+}