Testing Specials
Explore how to develop property-based tests for special pricing scenarios in Erlang using PropEr. Understand how to build complex custom generators that combine regular and special item lists to produce reliable expected prices. Learn to design tests that isolate special pricing logic for better bug detection and consistent results.
We'll cover the following...
Getting started
Rather than modifying the existing property, which does a fine job of checking non-special prices, we’ll add a new one to check specials. The separation will help narrow down problems when they happen. If the property for basic prices always works, then we’ll know that failures in the separate special property likely relate to bugs in the special one’s handling.
Let’s take a look at the property that we could implement.
prop_special() ->
?FORALL({ItemList, ExpectedPrice, PriceList, SpecialList},
item_price_special(),
ExpectedPrice =:= checkout:total(ItemList, PriceList, SpecialList)).
This property is similar to the one we wrote earlier, except that we now expect another term out of the generator, which is a list of ...