proptest-arbitrary-adapter

Provides the necessary glue to reuse an implementation of arbitrary::Arbitrary as a proptest::strategy::Strategy.

Usage

Assuming you use test-strategy (which you should), using a strategy for a type that implements arbitrary::Arbitrary is as simple as:

#[proptest]
fn my_test(#[strategy(arb())] my_type: MyType) {
    // …
}

Origin

This code is a copy of the unmaintained crate proptest-arbitrary-interop, with some additional improvements from open pull requests of the original's repository.

Caveats

It only works with types that implement arbitrary::Arbitrary in a particular fashion: those conforming to the requirements of ArbInterop. These are roughly "types that, when randomly-generated, don't retain pointers into the random-data buffer wrapped by the arbitrary::Unstructured they are generated from". Many implementations of arbitrary::Arbitrary will fit the bill, but certain kinds of "zero-copy" implementations of arbitrary::Arbitrary will not work. This requirement appears to be a necessary part of the semantic model of proptest – generated values have to own their pointer graph, no borrows. Patches welcome if you can figure out a way to not require it.