diff --git a/tests/xharness/MacTestProject.cs b/tests/xharness/MacTestProject.cs
index 78ccf1439e..4d45eac716 100644
--- a/tests/xharness/MacTestProject.cs
+++ b/tests/xharness/MacTestProject.cs
@@ -32,10 +32,6 @@ namespace Xharness {
 
 		public string Platform = "x86";
 
-		public MacTestProject () : base ()
-		{
-		}
-
 		public MacTestProject (string path, bool isExecutableProject = true, MacFlavors targetFrameworkFlavor = MacFlavors.Full | MacFlavors.Modern) : base (path, isExecutableProject)
 		{
 			TargetFrameworkFlavors = targetFrameworkFlavor;
@@ -43,10 +39,14 @@ namespace Xharness {
 
 		public override TestProject Clone ()
 		{
-			var rv = (MacTestProject) base.Clone ();
-			rv.TargetFrameworkFlavors = TargetFrameworkFlavors;
+			return CompleteClone (new MacTestProject (Path, IsExecutableProject, TargetFrameworkFlavors));
+		}
+
+		protected override TestProject CompleteClone (TestProject project)
+		{
+			var rv = (MacTestProject) project;
 			rv.Platform = Platform;
-			return rv;
+			return base.CompleteClone (rv);
 		}
 
 		public override string ToString ()
diff --git a/tests/xharness/TestProject.cs b/tests/xharness/TestProject.cs
index 2b984fe6d2..9b69ce639c 100644
--- a/tests/xharness/TestProject.cs
+++ b/tests/xharness/TestProject.cs
@@ -1,3 +1,5 @@
+#nullable enable
+
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -13,32 +15,28 @@ using Xharness.Jenkins.TestTasks;
 
 namespace Xharness {
 	public class TestProject {
-		XmlDocument xml;
+		XmlDocument? xml;
 		bool generate_variations = true;
 
 		public TestPlatform TestPlatform;
 		public string Path;
-		public string SolutionPath;
-		public string Name;
+		public string? SolutionPath;
+		public string? Name;
 		public bool IsExecutableProject;
 		public bool IsNUnitProject;
 		public bool IsDotNetProject;
-		public string [] Configurations;
-		public Func<Task> Dependency;
-		public string FailureMessage;
+		public string []? Configurations;
+		public Func<Task>? Dependency;
+		public string? FailureMessage;
 		public bool RestoreNugetsInProject = true;
-		public string MTouchExtraArgs;
+		public string? MTouchExtraArgs;
 		public double TimeoutMultiplier = 1;
 		public bool? Ignore;
 
-		public IEnumerable<TestProject> ProjectReferences;
+		public IEnumerable<TestProject>? ProjectReferences;
 
 		// Optional
-		public MonoNativeInfo MonoNativeInfo { get; set; }
-
-		public TestProject ()
-		{
-		}
+		public MonoNativeInfo? MonoNativeInfo { get; set; }
 
 		public TestProject (string path, bool isExecutableProject = true)
 		{
@@ -60,7 +58,11 @@ namespace Xharness {
 
 		public virtual TestProject Clone ()
 		{
-			TestProject rv = (TestProject) Activator.CreateInstance (GetType ());
+			return CompleteClone (new TestProject (Path, IsExecutableProject));
+		}
+
+		protected virtual TestProject CompleteClone (TestProject rv)
+		{
 			rv.Path = Path;
 			rv.IsExecutableProject = IsExecutableProject;
 			rv.IsDotNetProject = IsDotNetProject;
@@ -73,13 +75,6 @@ namespace Xharness {
 			return rv;
 		}
 
-		internal async Task<TestProject> CreateCloneAsync (ILog log, IProcessManager processManager, ITestTask test, string rootDirectory)
-		{
-			var rv = Clone ();
-			await rv.CreateCopyAsync (log, processManager, test, rootDirectory);
-			return rv;
-		}
-
 		public Task CreateCopyAsync (ILog log, IProcessManager processManager, ITestTask test, string rootDirectory)
 		{
 			var pr = new Dictionary<string, TestProject> ();
@@ -88,7 +83,7 @@ namespace Xharness {
 
 		async Task CreateCopyAsync (ILog log, IProcessManager processManager, ITestTask test, string rootDirectory, Dictionary<string, TestProject> allProjectReferences)
 		{
-			var directory = Cache.CreateTemporaryDirectory (test?.TestName ?? System.IO.Path.GetFileNameWithoutExtension (Path));
+			var directory = Cache.CreateTemporaryDirectory (test.TestName ?? System.IO.Path.GetFileNameWithoutExtension (Path));
 			Directory.CreateDirectory (directory);
 			var original_path = Path;
 			Path = System.IO.Path.Combine (directory, System.IO.Path.GetFileName (Path));
@@ -244,7 +239,7 @@ namespace Xharness {
 
 		public override string ToString ()
 		{
-			return Name;
+			return Name ?? base.ToString ();
 		}
 	}
 
diff --git a/tests/xharness/TestProjectExtensions.cs b/tests/xharness/TestProjectExtensions.cs
index 5ca1ea759c..160c304c77 100644
--- a/tests/xharness/TestProjectExtensions.cs
+++ b/tests/xharness/TestProjectExtensions.cs
@@ -52,10 +52,7 @@ namespace Xharness {
 				return null;
 			if (extensions.Count () != 1)
 				throw new NotImplementedException ();
-			return new TestProject
-			{
-				Path = Path.GetFullPath (Path.Combine (Path.GetDirectoryName (self.Path), Target.ProjectsDir, "today-extension", extensions.First ().Replace ('\\', '/'))),
-			};
+			return new TestProject (Path.GetFullPath (Path.Combine (Path.GetDirectoryName (self.Path), Target.ProjectsDir, "today-extension", extensions.First ().Replace ('\\', '/'))));
 		}
 	}
 }
diff --git a/tests/xharness/iOSTestProject.cs b/tests/xharness/iOSTestProject.cs
index 2c6fca728c..f086d419e6 100644
--- a/tests/xharness/iOSTestProject.cs
+++ b/tests/xharness/iOSTestProject.cs
@@ -12,10 +12,6 @@ namespace Xharness {
 		public bool SkipDeviceVariations;
 		public bool BuildOnly;
 
-		public iOSTestProject ()
-		{
-		}
-
 		public iOSTestProject (string path, bool isExecutableProject = true)
 			: base (path, isExecutableProject)
 		{
@@ -32,7 +28,12 @@ namespace Xharness {
 
 		public override TestProject Clone ()
 		{
-			var rv = (iOSTestProject) base.Clone ();
+			return CompleteClone (new iOSTestProject (Path, IsExecutableProject));
+		}
+
+		protected override TestProject CompleteClone (TestProject project)
+		{
+			var rv = (iOSTestProject) project;
 			rv.SkipiOSVariation = SkipiOSVariation;
 			rv.SkipwatchOSVariation = SkipwatchOSVariation;
 			rv.SkipwatchOSARM64_32Variation = SkipwatchOSARM64_32Variation;
@@ -41,7 +42,7 @@ namespace Xharness {
 			rv.SkipTodayExtensionVariation = SkipTodayExtensionVariation;
 			rv.SkipDeviceVariations = SkipDeviceVariations;
 			rv.BuildOnly = BuildOnly;
-			return rv;
+			return base.CompleteClone (rv);
 		}
 	}
 }