Add managed<->native marshalling tests

VpSharp.Tests/VpSharp.Tests.csproj

@@ -6,6 +6,8 @@
         <Nullable>enable</Nullable>
 
         <IsPackable>false</IsPackable>
+
+        <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     </PropertyGroup>
 
     <ItemGroup>

VpSharp.Tests/src/MarshellerTests.cs

@@ -0,0 +1,75 @@
+using System.Diagnostics;
+using System.Text;
+using VpSharp.Internal;
+
+namespace VpSharp.Tests;
+
+[TestClass]
+public class MarshellerTests
+{
+    private static readonly Utf8StringToNative ManagedToNativeMarshaller = new();
+    private static readonly Utf8StringToManaged NativeToManagedMarshaller = new();
+    private static readonly Random Random = new();
+
+    [TestMethod]
+    public unsafe void MarshalNativeToManaged_ShouldReturnPointerToUtf8Bytes_GivenString()
+    {
+        string value = GenerateRandomString();
+        byte* pointer = GetBytePointer(value, out int count);
+        string expected = Encoding.UTF8.GetString(pointer, count);
+        var actual = (string)NativeToManagedMarshaller.MarshalNativeToManaged((nint)pointer);
+        Assert.AreEqual(expected, actual);
+
+        CleanUpNativeData(pointer);
+    }
+
+    [TestMethod]
+    public unsafe void MarshalManagedToNative_ShouldReturnPointerToUtf8Bytes_GivenString()
+    {
+        string value = GenerateRandomString();
+        byte* pointer = GetBytePointer(value, out int count);
+        string result = Encoding.UTF8.GetString(pointer, count);
+
+        Trace.WriteLine($"Test string: {value}");
+        Assert.AreEqual(value, result);
+
+        CleanUpNativeData(pointer);
+    }
+
+    private static unsafe void CleanUpNativeData(byte* pointer)
+    {
+        ManagedToNativeMarshaller.CleanUpNativeData((nint)pointer);
+    }
+
+    private static string GenerateRandomString(int length = 50)
+    {
+        var builder = new StringBuilder();
+
+        for (var index = 0; index < length; index++)
+        {
+            int mode = Random.Next(0, 3);
+            switch (mode)
+            {
+                case 0:
+                    builder.Append((char)Random.Next('A', 'Z'));
+                    break;
+                case 1:
+                    builder.Append((char)Random.Next('a', 'z'));
+                    break;
+                default:
+                    builder.Append((char)Random.Next('0', '9'));
+                    break;
+            }
+        }
+
+        return builder.ToString();
+    }
+
+    private static unsafe byte* GetBytePointer(string input, out int byteCount)
+    {
+        var marshaller = new Utf8StringToNative();
+        nint buffer = marshaller.MarshalManagedToNative(input);
+        byteCount = Encoding.UTF8.GetByteCount(input);
+        return (byte*)buffer.ToPointer();
+    }
+}