Merge pull request #414 from dotnet/bugfix/mac-cryptofix

Switch to overridable platform check

Author: SteveSyfuhs

Kerberos.NET/Crypto/Pal/CryptoPal.cs

@@ -9,6 +9,11 @@ namespace Kerberos.NET.Crypto
 {
     public abstract class CryptoPal
     {
+        protected CryptoPal()
+        {
+            this.PlatformCheck();
+        }
+
         protected static bool IsWindows => OSPlatform.IsWindows;
 
         protected static bool IsLinux => OSPlatform.IsLinux;
@@ -18,7 +23,7 @@ public abstract class CryptoPal
         public static CryptoPal Platform => lazyPlatform.Value;
 
         private static readonly Lazy<CryptoPal> lazyPlatform
-            = new Lazy<CryptoPal>(() => CreatePal());
+            = new(() => CreatePal());
 
         private static Func<CryptoPal> injectedPal;
 
@@ -27,6 +32,10 @@ public static void RegisterPal(Func<CryptoPal> palFunc)
             injectedPal = palFunc ?? throw new InvalidOperationException("Cannot register a null PAL");
         }
 
+        protected virtual void PlatformCheck()
+        {
+        }
+
         private static CryptoPal CreatePal()
         {
             var injected = injectedPal;
@@ -40,15 +49,13 @@ private static CryptoPal CreatePal()
             {
                 return new WindowsCryptoPal();
             }
-
-            if (IsLinux)
+            else if (IsOsX)
             {
-                return new LinuxCryptoPal();
+                return new OSXCryptoPal();
             }
-
-            if (IsOsX)
+            else if (IsLinux)
             {
-                return new OSXCryptoPal();
+                return new LinuxCryptoPal();
             }
 
             throw PlatformNotSupported();

Kerberos.NET/Crypto/Pal/Linux/LinuxCryptoPal.cs

@@ -10,7 +10,7 @@ namespace Kerberos.NET.Crypto
 {
     public class LinuxCryptoPal : CryptoPal
     {
-        public LinuxCryptoPal()
+        protected override void PlatformCheck()
         {
             if (!IsLinux)
             {

Kerberos.NET/Crypto/Pal/OSX/OSXCryptoPal.cs

@@ -7,7 +7,7 @@ namespace Kerberos.NET.Crypto
 {
     public class OSXCryptoPal : LinuxCryptoPal
     {
-        public OSXCryptoPal()
+        protected override void PlatformCheck()
         {
             if (!IsOsX)
             {

Kerberos.NET/Crypto/Pal/Windows/WindowsCryptoPal.cs

@@ -10,7 +10,7 @@ namespace Kerberos.NET.Crypto
 {
     public class WindowsCryptoPal : CryptoPal
     {
-        public WindowsCryptoPal()
+        protected override void PlatformCheck()
         {
             if (!IsWindows)
             {