Enable multi-dim array interpreter test (#115916)

Expand and enable the multi-dim array interpreter test

Author: kg

src/tests/JIT/interpreter/Interpreter.cs

@@ -845,10 +845,11 @@ public static void RunInterpreterTests()
         Console.WriteLine("TestLdtoken");
         if (!TestLdtoken())
             Environment.FailFast(null);
-        /*
+
+        Console.WriteLine("TestMdArray");
         if (!TestMdArray())
             Environment.FailFast(null);
-        */
+
         Console.WriteLine("TestExceptionHandling");
         TestExceptionHandling();
 
@@ -2246,13 +2247,28 @@ public static bool TestLdtoken()
 
     public static bool TestMdArray()
     {
-        // FIXME: This generates roughly:
-        // newobj int[,].ctor
-        // ldtoken int[,]
-        // call System.Runtime.CompilerServices.RuntimeHelpers.InitializeArray
-        // The newobj currently fails because int[,].ctor isn't a real method, the interp needs to use getCallInfo to determine how to invoke it
         int[,] a = { { 1, 2 }, { 3, 4 } };
-        return a[0, 1] == 2;
+        if (a[0, 1] != 2)
+            return false;
+
+        object[,] b = new object[1, 1];
+        ref object bElt = ref b[0, 0];
+        bElt = null;
+
+        object[,] c = new string[1, 1];
+
+        try
+        {
+            ref object cElt = ref c[0, 0];
+            return false;
+        }
+        catch (ArrayTypeMismatchException)
+        {
+        }
+
+        ref readonly object cElt2 = ref c[0, 0];
+
+        return true;
     }
 
     private static int _fieldA;