Type Definition proptest::arbitrary::StrategyFor

type StrategyFor<A> = <A as Arbitrary>::Strategy;

StrategyFor allows you to mention the type of Strategy for the input type A without directly using associated types or without resorting to existential types. This way, if implementation of Arbitrary changes, your tests should not break. This can be especially beneficial when the type of Strategy that you are dealing with is very long in name (the case with generics).