Test | Address XUnit failure on Windows Principal functionality is not supported on this platform (#2469)

Author: Javad Rahnama

src/Microsoft.Data.SqlClient/tests/FunctionalTests/AlwaysEncryptedTests/SqlColumnEncryptionCertificateStoreProviderShould.cs

@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Security.Cryptography.X509Certificates;
 using System.Security.Principal;
 using System.Text;
@@ -495,22 +496,24 @@ public override IEnumerable<Object[]> GetData(MethodInfo testMethod)
             {
                 yield return new object[2] { StoreLocation.CurrentUser, CurrentUserMyPathPrefix };
                 // use localmachine cert path only when current user is Admin.
-                if (CertificateFixture.IsAdmin)
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && CertificateFixture.IsAdmin)
                 {
                     yield return new object[2] { StoreLocation.LocalMachine, LocalMachineMyPathPrefix };
                 }
             }
         }
 
+
         public class ValidCertificatePathsParameters : DataAttribute
         {
+
             public override IEnumerable<Object[]> GetData(MethodInfo testMethod)
             {
                 yield return new object[2] { CurrentUserMyPathPrefix, StoreLocation.CurrentUser };
                 yield return new object[2] { MyPathPrefix, null };
                 yield return new object[2] { @"", null };
                 // use localmachine cert path only when current user is Admin.
-                if (CertificateFixture.IsAdmin)
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && CertificateFixture.IsAdmin)
                 {
                     yield return new object[2] { LocalMachineMyPathPrefix, StoreLocation.LocalMachine };
                 }
@@ -653,7 +656,7 @@ public CertificateFixture()
             AddCertificateToStore(certificate1, StoreLocation.CurrentUser);
             AddCertificateToStore(certificate2, StoreLocation.CurrentUser);
             AddCertificateToStore(certificate3, StoreLocation.CurrentUser);
-            if (IsAdmin)
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && IsAdmin)
             {
                 AddCertificateToStore(certificate3, StoreLocation.LocalMachine);
             }