add duplicate joint test

Assets/VRM/Tests/VRMSpringBoneTests.cs

@@ -0,0 +1,31 @@
+using System.IO;
+using System.Linq;
+using NUnit.Framework;
+using UnityEngine;
+
+namespace VRM
+{
+    public class VRMSpringBoneTests
+    {
+        static string AliciaPath
+        {
+            get
+            {
+                return Path.GetFullPath(Application.dataPath + "/../Tests/Models/Alicia_vrm-0.51/AliciaSolid_vrm-0.51.vrm")
+                    .Replace("\\", "/");
+            }
+        }
+
+        [Test]
+        public void DuplicatedJoints()
+        {
+            using var loaded = TestVrm0X.LoadPathAsBuiltInRP(AliciaPath);
+            var sb = loaded.GetComponentInChildren<VRMSpringBone>();
+
+            // make duplicate #2617
+            sb.RootBones.Add(sb.RootBones[0].GetChild(0));
+
+            Assert.DoesNotThrow(() => sb.Setup());
+        }
+    }
+}

Assets/VRM/Tests/VRMSpringBoneTests.cs.meta

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