@Test
public void test_greater_null() {

  FunctionExpression greater = dsl.greater(DSL.literal(1),
      DSL.ref(INT_TYPE_NULL_VALUE_FIELD, INTEGER));
  assertEquals(BOOLEAN, greater.type());
  assertEquals(LITERAL_NULL, greater.valueOf(valueEnv()));
  greater = dsl.greater(DSL.ref(INT_TYPE_NULL_VALUE_FIELD, INTEGER), DSL.literal(1));
  assertEquals(BOOLEAN, greater.type());
  assertEquals(LITERAL_NULL, greater.valueOf(valueEnv()));
  greater = dsl.greater(DSL.ref(INT_TYPE_NULL_VALUE_FIELD, INTEGER),
      DSL.ref(INT_TYPE_NULL_VALUE_FIELD, INTEGER));
  assertEquals(BOOLEAN, greater.type());
  assertEquals(LITERAL_NULL, greater.valueOf(valueEnv()));
}