Add test coverage for structs containing refs

Author: kg

src/tests/JIT/interpreter/Interpreter.cs

@@ -38,6 +38,17 @@ public MyStruct2(int val)
     }
 }
 
+public struct StructWithRefs
+{
+    public MyObj o1, o2;
+
+    public StructWithRefs(int val1, int val2)
+    {
+        o1 = new MyObj(val1);
+        o2 = new MyObj(val2);
+    }
+}
+
 public class InterpreterTest
 {
     static int Main(string[] args)
@@ -66,6 +77,8 @@ public static void RunInterpreterTests()
             Environment.FailFast(null);
         if (!TestFields())
             Environment.FailFast(null);
+        if (!TestStructRefFields())
+            Environment.FailFast(null);
         // FIXME: Calling TestSpecialFields causes the following System.GC.Collect to fail.
         /*
         if (!TestSpecialFields())
@@ -185,6 +198,24 @@ public static bool TestFields()
         return true;
     }
 
+    public static bool TestStructRefFields()
+    {
+        StructWithRefs s = new StructWithRefs(3, 42);
+        if (s.o1.str.a != 3)
+            return false;
+        if (s.o2.str.a != 42)
+            return false;
+
+        System.GC.Collect();
+
+        if (s.o1.str.a != 3)
+            return false;
+        if (s.o2.str.a != 42)
+            return false;
+
+        return true;
+    }
+
     [ThreadStatic]
     public static MyObj threadStaticObj;
     [ThreadStatic]