@Test
public void test_like_null() {

  FunctionExpression like =
      dsl.like(DSL.literal("str"), DSL.ref(STRING_TYPE_NULL_VALUE_FILED, STRING));
  assertEquals(BOOLEAN, like.type());
  assertEquals(LITERAL_NULL, like.valueOf(valueEnv()));
  like = dsl.like(DSL.ref(STRING_TYPE_NULL_VALUE_FILED, STRING), DSL.literal("str"));
  assertEquals(BOOLEAN, like.type());
  assertEquals(LITERAL_NULL, like.valueOf(valueEnv()));
  like = dsl.like(DSL.ref(STRING_TYPE_NULL_VALUE_FILED, STRING),
      DSL.ref(STRING_TYPE_NULL_VALUE_FILED, STRING));
  assertEquals(BOOLEAN, like.type());
  assertEquals(LITERAL_NULL, like.valueOf(valueEnv()));
}