Proptest, Arbitrary

NOTE: This version is still WIP; don't use yet, just reserving at crates.io.

Proptest is a property testing framework (i.e., the QuickCheck family) inspired by the Hypothesis framework for Python.

This crate, proptest-arbitrary, additionally provides an Arbitrary trait which allows you to have a canonical Strategy per type. This is the equivalent of Haskell QuickCheck's implementation of Arbitrary. In this interpretation of Arbitray, Strategy is the equivalent of the Gen monad.

Arbitrary is currently implemented as:

# extern crate proptest;
# use std::fmt::Debug;
# use proptest::strategy::{Strategy, ValueTree};

/// Arbitrary determines a canonical Strategy for the implementing type.
///
/// ...
pub trait Arbitrary : Sized + Debug {
    /// Generates a Strategy for producing arbitrary values of type the
    /// implementing type (Self).
    fn arbitrary() -> Self::Strategy;

    /// The type of ValueTree used for Self's Strategy.
    ///
    /// NOTE:
    /// This type should NOT be relied upon outside of this crate other than
    /// for implementing Arbitrary for other types.
    type ValueTree: ValueTree<Value = Self>;

    /// The type of Strategy used to generate values of type Self.
    ///
    /// NOTE:
    /// This type should NOT be relied upon outside of this crate other than
    /// for implementing Arbitrary for other types.
    type Strategy: Strategy<Value = Self::ValueTree>;
}

# fn main() {}

Status of this crate

This crate is currently experimental. It will hopefully be included in proptest in the future.

The current definition of the Arbitrary trait might change in the future pending the development of existential types in Rust. However, as long as you don't rely on Arbitrary having associated types in calling Arbitrary, in practice, this should not be a problem.

This crate mostly just contains Arbitrary and implementations for it. Hence, it is unlikely to see breaking change. If any change occurs, it will likely be new implementations or newtypes around common types.

See the changelog for a full list of substantial historical changes, breaking and otherwise.

Acknowledgements

TODO

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.