public void Test_two_As_are_100()
 {
     var checkout = new Checkout(this,_prices);
     checkout.Scan("A");
     checkout.Scan("A");
     Assert.AreEqual(_displayValue, 100);
 }
 private void CheckPriceForItemIsCorrect(Checkout checkout, string item)
 {
     checkout.Scan(item);
     Assert.AreEqual(_displayValue, _prices[item]);
 }