Add regression test

tests/Jellyfin.MediaEncoding.Tests/Encoder/ApplePlatformHelperTests.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Runtime.Versioning;
+using MediaBrowser.MediaEncoding.Encoder;
+using Xunit;
+
+namespace Jellyfin.MediaEncoding.Tests;
+
+[SupportedOSPlatform("macos")]
+public class ApplePlatformHelperTests
+{
+    [Fact]
+    public void GetSysctlValue_CpuBrand_NotEmpty()
+    {
+        Assert.SkipUnless(OperatingSystem.IsMacOS(), "macOS-only test");
+
+        Assert.NotEmpty(ApplePlatformHelper.GetSysctlValue("machdep.cpu.brand_string"));
+    }
+}