Fix broken unit and package tests

Author: CharliePoole

src/NUnitEngine/nunit.engine.core/DotNetHelper.cs

@@ -84,7 +84,7 @@ private static IEnumerable<RuntimeInfo> GetAllRuntimes(bool x86)
             foreach (string line in DotnetCommand("--list-runtimes", x86: x86))
             {
                 string[] parts = line.Trim().Split([' '], 3);
-                yield return new RuntimeInfo(parts[0], parts[1] + ".0", parts[2].Trim(['[', ']']));
+                yield return new RuntimeInfo(parts[0], parts[1], parts[2].Trim(['[', ']']));
             }
         }
 

src/NUnitEngine/nunit.engine.core/Internal/PathUtils.cs

@@ -144,10 +144,10 @@ public static bool SamePathOrUnder( string path1, string path2 )
 
             // if lengths are the same, check for equality
             if ( length1 == length2 )
-                return string.Compare( path1, path2, OS.IsWindows ) == 0;
+                return string.Compare( path1, path2, RunningOnWindows ) == 0;
 
             // path 2 is longer than path 1: see if initial parts match
-            if ( string.Compare( path1, path2.Substring( 0, length1 ), OS.IsWindows) != 0 )
+            if ( string.Compare( path1, path2.Substring( 0, length1 ), RunningOnWindows) != 0 )
                 return false;
 
             // must match through or up to a directory separator boundary
@@ -174,11 +174,13 @@ public static string Combine(string path1, params string[] morePaths)
         /// <exception cref="ArgumentNullException"><paramref name="path"/></exception>
         public static bool IsFullyQualifiedPath(string path )
         {
-            return OS.IsWindows
+            return RunningOnWindows
                 ? IsFullyQualifiedWindowsPath(path)
                 : IsFullyQualifiedUnixPath(path);
         }
 
+        private static bool RunningOnWindows => DirectorySeparatorChar == '\\';
+
         /// <summary>
         /// Returns a value that indicates whether the specified file path is fully qualified or not on Windows operating systems.
         /// </summary>
@@ -275,7 +277,7 @@ private static string[] SplitPath(string path)
 
         private static bool PathsEqual(string path1, string path2)
         {
-            if (OS.IsWindows)
+            if (RunningOnWindows)
                 return path1.ToLower().Equals(path2.ToLower());
             else
                 return path1.Equals(path2);

src/NUnitEngine/nunit.engine/Services/AgentProcess.cs

@@ -69,7 +69,7 @@ public AgentProcess(TestAgency agency, TestPackage package, Guid agentId)
 
                 if (runAsX86)
                 {
-                    if (OS.IsWindows)
+                    if (!OS.IsWindows)
                         throw new Exception("Running .NET Core as X86 is currently only supported on Windows");
 
                     if (!File.Exists(StartInfo.FileName))