Add NativeAOT smoke tests for resetting apartment state

Author: jkotas

src/tests/nativeaot/SmokeTests/UnitTests/Threading.cs

@@ -15,6 +15,12 @@ internal static class Threading
 
     public static int Run()
     {
+        if (OperatingSystem.IsWindows())
+        {
+            Console.WriteLine("    ApartmentTests");
+            ApartmentTests.ResetApartmentStatus();
+        }
+
         Console.WriteLine("    WaitSubsystemTests.DoubleSetOnEventWithTimedOutWaiterShouldNotStayInWaitersList");
         WaitSubsystemTests.DoubleSetOnEventWithTimedOutWaiterShouldNotStayInWaitersList();
 
@@ -121,6 +127,26 @@ public static int Run()
     }
 }
 
+internal static class ApartmentTests
+{
+    [Fact]
+    public static void ResetApartmentStatus()
+    {
+        Assert.Equal(ApartmentState.MTA, Thread.CurrentThread.GetApartmentState());
+
+        Thread.CurrentThread.SetApartmentState(ApartmentState.Unknown);
+        Assert.Equal(ApartmentState.MTA, Thread.CurrentThread.GetApartmentState());
+
+        Thread.CurrentThread.SetApartmentState(ApartmentState.STA);
+        Assert.Equal(ApartmentState.STA, Thread.CurrentThread.GetApartmentState());
+
+        Thread.CurrentThread.SetApartmentState(ApartmentState.Unknown);
+        Assert.Equal(ApartmentState.MTA, Thread.CurrentThread.GetApartmentState());
+
+        Thread.CurrentThread.SetApartmentState(ApartmentState.MTA);
+    }
+}
+
 internal static class WaitSubsystemTests
 {
     private const int AcceptableEarlyWaitTerminationDiffMilliseconds = -100;