public async Task IsValid_SalesPersonIDCheck()
{
var soh = new SalesOrderHeaders();
var toValidate = await soh.SingleAsync(new { SalesOrderID = 45816 });
// is invalid
Assert.AreEqual(1, soh.IsValid(toValidate).Count);
toValidate = await soh.SingleAsync(new { SalesOrderID = 45069 });
// is valid
Assert.AreEqual(0, soh.IsValid(toValidate).Count);
}