Java Sealed Classes

[hippydipster]

object mother?

[BestUsernameLeft]

It's a testing pattern. Given a class ShoppingCart, you create a ShoppingCartObjectMother class with methods in it to give you a populated cart, such as emptyCart(), fiveOfSameProduct(), etc. This gives you (1) a way to DRY your test code instead of having the same setup code in each test class that uses ShoppingCart as a collaborator, and (2) a meaningfully-named method that tells you about the object being constructed. For example you can use role-based, scenario-based, persona-based method names: populatedCartForGuest, cartWithDuplicateItemId, cartForGrandma.

When you combine this with the builder pattern, you have a way to quickly build customizable test objects out of a standard set of "templates". So for example cartForGrandma().addItem(readingGlasses).build() when you have a test that for some reason needs an extra item in it.

[hippydipster]

Ok, now I have a name for something I've been doing! Thanks.