diff --git a/CHANGELOG.md b/CHANGELOG.md
index 03ce9d6..608d9b1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,10 +7,13 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased] - yyyy-mm-dd
 
 ### Added
+- Added RcSpans UnitTest
+ 
 ### Fixed
 ### Changed
 ### Removed
 ### Special Thanks
+- [@Doprez](https://github.com/Doprez)
 
 
 ## [2024.2.1] - 2024-05-04
@@ -20,7 +23,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Added struct DtCrowdScopedTimer to avoid allocations in scoped timer calls. [@wrenge](https://github.com/wrenge)
 - Added struct RcScopedTimer to avoid allocations in RcContext scoped timer [@ikpil](https://github.com/ikpil)
 - Added RcSpans [@ikpil](https://github.com/ikpil)
-- 
+ 
 ### Fixed
 - SOH issue [#14](https://github.com/ikpil/DotRecast/issues/41)
 - Optimization: reduce number of allocations on hot path. [@awgil](https://github.com/awgil)
diff --git a/src/DotRecast.Core/RcSpans.cs b/src/DotRecast.Core/RcSpans.cs
index 474f492..283defc 100644
--- a/src/DotRecast.Core/RcSpans.cs
+++ b/src/DotRecast.Core/RcSpans.cs
@@ -6,17 +6,25 @@ namespace DotRecast.Core
     public static class RcSpans
     {
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Copy<T>(Span<T> source, Span<T> destination)
+        public static void Copy<T>(Span<T> src, Span<T> dst)
         {
-            Copy(source, 0, destination, 0, source.Length);
-        }
-        
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Copy<T>(Span<T> source, int sourceIdx, Span<T> destination, int destinationIdx, int length)
-        {
-            var src = source.Slice(sourceIdx, length);
-            var dst = destination.Slice(destinationIdx);
             src.CopyTo(dst);
         }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Copy<T>(Span<T> src, int srcIdx, Span<T> dst, int dstIdx, int length)
+        {
+            var slicedSrc = src.Slice(srcIdx, length);
+            var slicedDst = dst.Slice(dstIdx);
+            slicedSrc.CopyTo(slicedDst);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void Move<T>(Span<T> src, int srcIdx, int dstIdx, int length)
+        {
+            var slicedSrc = src.Slice(srcIdx, length);
+            var slicedDst = src.Slice(dstIdx, length);
+            slicedSrc.CopyTo(slicedDst);
+        }
     }
 }
\ No newline at end of file
diff --git a/test/DotRecast.Core.Test/RcSpanTest.cs b/test/DotRecast.Core.Test/RcSpanTest.cs
new file mode 100644
index 0000000..268db7a
--- /dev/null
+++ b/test/DotRecast.Core.Test/RcSpanTest.cs
@@ -0,0 +1,148 @@
+using System;
+using System.Collections.Generic;
+using NUnit.Framework;
+
+namespace DotRecast.Core.Test;
+
+public class RcSpanTest
+{
+    [Test]
+    public void TestCopy()
+    {
+        // Test for copying all elements to the destination span.
+        {
+            Span<long> src = stackalloc long[] { 1, 2, 3 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            RcSpans.Copy(src, dst);
+            Assert.That(src.ToArray(), Is.EqualTo(dst.ToArray()));
+        }
+
+        // Test for successful copying when the destination Span has a larger size.
+        {
+            Span<long> src = stackalloc long[] { 1, 2 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0, 0 };
+
+            RcSpans.Copy(src, dst);
+            Assert.That(src.ToArray(), Is.EqualTo(dst.Slice(0, src.Length).ToArray()));
+        }
+
+        // Test for an error when copying to a Span with a smaller size.
+        {
+            Assert.Throws<ArgumentException>(() =>
+            {
+                Span<long> src = stackalloc long[] { 1, 2, 3, 4, 5 };
+                Span<long> dst = stackalloc long[] { 0, 0, 0 };
+                RcSpans.Copy(src, dst);
+            });
+        }
+
+        // Test for copying a specific range of elements from the source span to a specific range in the destination span.
+        {
+            Span<long> src = stackalloc long[] { 1, 2, 3, 4, 5 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            RcSpans.Copy(src, 2, dst, 0, 2);
+            Assert.That(src.Slice(2, 2).ToArray(), Is.EqualTo(dst.Slice(0, 2).ToArray()));
+        }
+
+        // Test for copying a specific range of elements from the source span to a specific range in the destination span.
+        {
+            Span<long> src = stackalloc long[] { 5, 4, 3, 2, 1 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            RcSpans.Copy(src, 2, dst, 0, 3);
+            Assert.That(src.Slice(2, 3).ToArray(), Is.EqualTo(dst.ToArray()));
+        }
+
+        // Test for src (index + length) over
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 5, 4, 3, 2, 1 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            //
+            RcSpans.Copy(src, 3, dst, 0, 3);
+        });
+
+        // Test for src (index + length) over
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 5, 4, 3, 2, 1 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            //
+            RcSpans.Copy(src, 5, dst, 0, 1);
+        });
+
+
+        // Test for dst (idx + length) over 
+        Assert.Throws<ArgumentException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 5, 4, 3, 2, 1 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            //
+            RcSpans.Copy(src, 0, dst, 1, 3);
+        });
+
+        // Test for dst (idx + length) over 
+        Assert.Throws<ArgumentException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 5, 4, 3, 2, 1 };
+            Span<long> dst = stackalloc long[] { 0, 0, 0 };
+
+            //
+            RcSpans.Copy(src, 0, dst, 0, 4);
+        });
+    }
+
+    [Test]
+    public void TestMove()
+    {
+        // [3, 2, 1] -> [3, 1, 1]
+        {
+            var expected = new List<long>() { 3, 1, 1 };
+            Span<long> src = stackalloc long[] { 3, 2, 1 };
+            RcSpans.Move(src, 2, 1, 1);
+            Assert.That(src.ToArray(), Is.EqualTo(expected));
+        }
+
+        // [3, 2, 1] -> [2, 1, 1]
+        {
+            var expected = new List<long>() { 2, 1, 1 };
+            Span<long> src = stackalloc long[] { 3, 2, 1 };
+            RcSpans.Move(src, 1, 0, 2);
+            Assert.That(src.ToArray(), Is.EqualTo(expected));
+        }
+
+        // [3, 2, 1] -> [3, 2, 1]
+        {
+            var expected = new List<long>() { 3, 2, 1 };
+            Span<long> src = stackalloc long[] { 3, 2, 1 };
+            RcSpans.Move(src, 0, 0, 3);
+            Assert.That(src.ToArray(), Is.EqualTo(expected));
+        }
+
+        // length over
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 3, 2, 1 };
+            RcSpans.Move(src, 0, 0, 4);
+        });
+        
+        // source index over
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 3, 2, 1 };
+            RcSpans.Move(src, 3, 0, 1);
+        });
+        
+        // destination index over
+        Assert.Throws<ArgumentOutOfRangeException>(() =>
+        {
+            Span<long> src = stackalloc long[] { 3, 2, 1 };
+            RcSpans.Move(src, 0, 3, 1);
+        });
+    }
+}
\ No newline at end of file