public final void testZeroMinusExp() {
   Minus m = new Minus();
   m.type = IntegerType.instance;
   operationWithZero(m, Minus.class, true, true);
 }
 public final void testExpMinusZero() {
   Minus m = new Minus();
   m.type = IntegerType.instance;
   operationWithZero(m, null, false, true);
 }