feat: Implements passive Detect Hidden mechanics (#2342)

Projects/UOContent.Tests/Tests/Skills/DetectHiddenTests.cs

@@ -0,0 +1,213 @@
+using Server;
+using Server.Mobiles;
+using Server.SkillHandlers;
+using Server.Tests;
+using Xunit;
+
+namespace UOContent.Tests;
+
+[Collection("Sequential UOContent Tests")]
+public class DetectHiddenTests
+{
+    // All coordinates use Y=500 to stay well within Felucca's 7168x4096 boundary.
+    // X values are spread 200 tiles apart to avoid overlap with each other and
+    // with the Tracking tests that use coordinates around (1000-4000, 1000-4000).
+
+    /// <summary>
+    /// A detector with higher Detect Hidden than the stealther's Hiding should reveal them.
+    /// With PredictableRandom both rolls get the same offset, so detection succeeds
+    /// when detectSkill >= hiding.
+    /// </summary>
+    [Fact]
+    public void TryDetectStealther_Reveals_WhenDetectSkillExceedsHiding()
+    {
+        using var rng = new PredictableRandom(10);
+        DetectHidden.ClearDebounceCache();
+        var map = Map.Felucca;
+        var detector = CreatePlayerMobile(map, new Point3D(1000, 500, 0));
+        var stealther = CreatePlayerMobile(map, new Point3D(1001, 500, 0));
+
+        try
+        {
+            detector.Skills.DetectHidden.BaseFixedPoint = 600; // 60.0
+            stealther.Skills.Hiding.BaseFixedPoint = 500;      // 50.0
+            stealther.Hidden = true;
+
+            var result = DetectHidden.TryDetectStealther(detector, stealther);
+
+            Assert.True(result);
+            Assert.False(stealther.Hidden);
+        }
+        finally
+        {
+            detector.Delete();
+            stealther.Delete();
+            DetectHidden.ClearDebounceCache();
+        }
+    }
+
+    /// <summary>
+    /// When detect skill exactly equals hiding, detection succeeds (ss >= ts).
+    /// </summary>
+    [Fact]
+    public void TryDetectStealther_Reveals_WhenSkillsAreEqual()
+    {
+        using var rng = new PredictableRandom(10);
+        DetectHidden.ClearDebounceCache();
+        var map = Map.Felucca;
+        var detector = CreatePlayerMobile(map, new Point3D(1200, 500, 0));
+        var stealther = CreatePlayerMobile(map, new Point3D(1201, 500, 0));
+
+        try
+        {
+            detector.Skills.DetectHidden.BaseFixedPoint = 500; // 50.0
+            stealther.Skills.Hiding.BaseFixedPoint = 500;      // 50.0
+            stealther.Hidden = true;
+
+            var result = DetectHidden.TryDetectStealther(detector, stealther);
+
+            Assert.True(result);
+            Assert.False(stealther.Hidden);
+        }
+        finally
+        {
+            detector.Delete();
+            stealther.Delete();
+            DetectHidden.ClearDebounceCache();
+        }
+    }
+
+    /// <summary>
+    /// When hiding skill exceeds detect skill, detection fails.
+    /// </summary>
+    [Fact]
+    public void TryDetectStealther_DoesNotReveal_WhenHidingExceedsDetectSkill()
+    {
+        using var rng = new PredictableRandom(10);
+        DetectHidden.ClearDebounceCache();
+        var map = Map.Felucca;
+        var detector = CreatePlayerMobile(map, new Point3D(1400, 500, 0));
+        var stealther = CreatePlayerMobile(map, new Point3D(1401, 500, 0));
+
+        try
+        {
+            detector.Skills.DetectHidden.BaseFixedPoint = 500; // 50.0
+            stealther.Skills.Hiding.BaseFixedPoint = 600;      // 60.0
+            stealther.Hidden = true;
+
+            var result = DetectHidden.TryDetectStealther(detector, stealther);
+
+            Assert.False(result);
+            Assert.True(stealther.Hidden);
+        }
+        finally
+        {
+            detector.Delete();
+            stealther.Delete();
+            DetectHidden.ClearDebounceCache();
+        }
+    }
+
+    /// <summary>
+    /// A detector with zero Detect Hidden skill should never passively detect anyone.
+    /// Uses Elf race since Humans get a 20.0 racial bonus (Jack of All Trades).
+    /// </summary>
+    [Fact]
+    public void TryDetectStealther_DoesNotReveal_WhenDetectorHasNoSkill()
+    {
+        using var rng = new PredictableRandom(10);
+        DetectHidden.ClearDebounceCache();
+        var map = Map.Felucca;
+        var detector = CreatePlayerMobile(map, new Point3D(1600, 500, 0));
+        var stealther = CreatePlayerMobile(map, new Point3D(1601, 500, 0));
+
+        try
+        {
+            detector.Race = Race.Elf;
+            detector.Skills.DetectHidden.BaseFixedPoint = 0; // 0.0
+            stealther.Skills.Hiding.BaseFixedPoint = 0;      // 0.0
+            stealther.Hidden = true;
+
+            var result = DetectHidden.TryDetectStealther(detector, stealther);
+
+            Assert.False(result);
+            Assert.True(stealther.Hidden);
+        }
+        finally
+        {
+            detector.Delete();
+            stealther.Delete();
+            DetectHidden.ClearDebounceCache();
+        }
+    }
+
+    /// <summary>
+    /// TryDetectStealther is a no-op when the target is not actually hidden.
+    /// </summary>
+    [Fact]
+    public void TryDetectStealther_DoesNothing_WhenStealtherIsNotHidden()
+    {
+        using var rng = new PredictableRandom(10);
+        DetectHidden.ClearDebounceCache();
+        var map = Map.Felucca;
+        var detector = CreatePlayerMobile(map, new Point3D(1800, 500, 0));
+        var stealther = CreatePlayerMobile(map, new Point3D(1801, 500, 0));
+
+        try
+        {
+            detector.Skills.DetectHidden.BaseFixedPoint = 1000;
+            stealther.Hidden = false;
+
+            var result = DetectHidden.TryDetectStealther(detector, stealther);
+
+            Assert.False(result);
+            Assert.False(stealther.Hidden);
+        }
+        finally
+        {
+            detector.Delete();
+            stealther.Delete();
+            DetectHidden.ClearDebounceCache();
+        }
+    }
+
+    /// <summary>
+    /// Passive detection only works on Felucca. A stealther on Trammel
+    /// should never be revealed by passive detection.
+    /// </summary>
+    [Fact]
+    public void TryDetectStealther_DoesNotReveal_WhenNotOnFelucca()
+    {
+        using var rng = new PredictableRandom(10);
+        DetectHidden.ClearDebounceCache();
+        var map = Map.Trammel;
+        var detector = CreatePlayerMobile(map, new Point3D(2000, 500, 0));
+        var stealther = CreatePlayerMobile(map, new Point3D(2001, 500, 0));
+
+        try
+        {
+            detector.Skills.DetectHidden.BaseFixedPoint = 1000; // 100.0
+            stealther.Skills.Hiding.BaseFixedPoint = 0;         // 0.0
+            stealther.Hidden = true;
+
+            var result = DetectHidden.TryDetectStealther(detector, stealther);
+
+            Assert.False(result);
+            Assert.True(stealther.Hidden);
+        }
+        finally
+        {
+            detector.Delete();
+            stealther.Delete();
+            DetectHidden.ClearDebounceCache();
+        }
+    }
+
+    private static PlayerMobile CreatePlayerMobile(Map map, Point3D location)
+    {
+        var mobile = new PlayerMobile(World.NewMobile);
+        mobile.DefaultMobileInit();
+        mobile.MoveToWorld(location, map);
+        return mobile;
+    }
+}