public void ShoulBuildQueryString()
{
// arrange
Transaction tx = new Transaction { Tx = "ABC", Amount = "123" };
// act
QueryString qs = tx.ToPdtQueryString();
// assert
Assert.AreEqual(7, qs.Count);
Assert.AreEqual("?tx=ABC&st=&amt=123&cc=&cm=&item_number=&business=", qs.ToString());
}