fix the runtime check for msbuild testing

Author: arturcic

src/GitVersion.MsBuild.Tests/Helpers/EnvironmentHelper.cs

@@ -0,0 +1,20 @@
+namespace GitVersion.MsBuild.Tests.Helpers
+{
+    internal static class EnvironmentHelper
+    {
+#if NETCORE || NETCOREAPP
+        private static bool? _isCoreClr;
+#endif
+
+        public static bool IsCoreClr()
+        {
+#if NETCORE || NETCOREAPP
+            _isCoreClr ??= System.Environment.Version.Major >= 5
+                           || System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription.StartsWith(".NET Core");
+            return _isCoreClr.Value;
+#else
+            return false;
+#endif
+        }
+    }
+}

src/GitVersion.MsBuild.Tests/Helpers/MsBuildExeFixture.cs

@@ -8,7 +8,6 @@
 using Microsoft.Build.Framework;
 using Microsoft.Build.Logging;
 using Microsoft.Build.Utilities.ProjectCreation;
-using NUnit.Framework.Internal;
 using StringWriter = System.IO.StringWriter;
 
 namespace GitVersion.MsBuild.Tests.Helpers
@@ -69,12 +68,9 @@ public MsBuildExeFixtureResult Execute()
 
         public void CreateTestProject(Action<ProjectCreator> extendProject)
         {
-            var project = RuntimeFramework.CurrentFramework.Runtime switch
-            {
-                RuntimeType.NetCore => ProjectCreator.Templates.SdkCsproj(ProjectPath),
-                RuntimeType.Net => ProjectCreator.Templates.LegacyCsproj(ProjectPath, defaultTargets: null, targetFrameworkVersion: "v4.8", toolsVersion: "15.0"),
-                _ => null
-            };
+            var project = EnvironmentHelper.IsCoreClr()
+                ? ProjectCreator.Templates.SdkCsproj(ProjectPath)
+                : ProjectCreator.Templates.LegacyCsproj(ProjectPath, defaultTargets: null, targetFrameworkVersion: "v4.8", toolsVersion: "15.0");
 
             if (project == null) return;