Fixed IsNotInstanceOfType failing when objected being asserted on is null (#622)

* Update Assert.cs

* Update Assert.cs

* Update AssertTests.cs

* Update Assert.cs

* Update Assert.cs

Author: ShreyasRmsft

src/TestFramework/MSTest.Core/Assertions/Assert.cs

@@ -1754,11 +1754,17 @@ public static void IsNotInstanceOfType(object value, Type wrongType, string mess
         /// </exception>
         public static void IsNotInstanceOfType(object value, Type wrongType, string message, params object[] parameters)
         {
-            if (wrongType == null || value == null)
+            if (wrongType == null)
             {
                 HandleFail("Assert.IsNotInstanceOfType", message, parameters);
             }
 
+            // Null is not an instance of any type.
+            if (value == null)
+            {
+                return;
+            }
+
             var elementTypeInfo = value.GetType().GetTypeInfo();
             var expectedTypeInfo = wrongType.GetTypeInfo();
             if (expectedTypeInfo.IsAssignableFrom(elementTypeInfo))

test/UnitTests/MSTest.Core.Unit.Tests/Assertions/AssertTests.cs

@@ -278,7 +278,6 @@ public void InstanceOfTypeShouldPassOnHigherInstance()
         public void InstanceNotOfTypeShouldFailWhenValueIsNull()
         {
             Action action = () => TestFrameworkV2.Assert.IsNotInstanceOfType(null, typeof(AssertTests));
-            ActionUtility.ActionShouldThrowExceptionOfType(action, typeof(TestFrameworkV2.AssertFailedException));
         }
 
         [TestMethod]