Trait Arbitrary

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pub trait Arbitrary: Sized + Debug {
    type Parameters: Default;
    type Strategy: Strategy<Value = Self>;

    // Required method
    fn arbitrary_with(args: Self::Parameters) -> Self::Strategy;

    // Provided method
    fn arbitrary() -> Self::Strategy { ... }
}

Expand description

Arbitrary determines a canonical Strategy for the implementing type.

It provides the method arbitrary_with which generates a Strategy for producing arbitrary values of the implementing type (Self). In general, these strategies will produce the entire set of values possible for the type, up to some size limitation or constraints set by their parameters. When this is not desired, strategies to produce the desired values can be built by combining Strategys as described in the crate documentation.

This trait analogous to Haskell QuickCheck’s implementation of Arbitrary. In this interpretation of Arbitrary, Strategy is the equivalent of the Gen monad. Unlike in QuickCheck, Arbitrary is not a core component; types do not need to implement Arbitrary unless one wants to use any or other free functions in this module.

Arbitrary currently only works for types which represent owned data as opposed to borrowed data. This is a fundamental restriction of proptest which may be lifted in the future as the generic associated types (GAT) feature of Rust is implemented and stabilized.

If you do not have unique constraints on how to generate the data for your custom types, consider using the derive macro to implement Arbitrary

Required Associated Types§

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type Parameters: Default

The type of parameters that arbitrary_with accepts for configuration of the generated Strategy. Parameters must implement Default.

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type Strategy: Strategy<Value = Self>

The type of Strategy used to generate values of type Self.

Required Methods§

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fn arbitrary_with(args: Self::Parameters) -> Self::Strategy

Generates a Strategy for producing arbitrary values of type the implementing type (Self). The strategy is passed the arguments given in args.

If you wish to use the default() arguments, use arbitrary instead.

Provided Methods§

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fn arbitrary() -> Self::Strategy

Generates a Strategy for producing arbitrary values of type the implementing type (Self).

Calling this for the type X is the equivalent of using X::arbitrary_with(Default::default()).

This method is defined in the trait for optimization for the default if you want to do that. It is a logic error to not preserve the semantics when overriding.

Object Safety§

This trait is not object safe.

Trait ArbitraryCopy item path

Required Associated Types§

type Parameters: Default

type Strategy: Strategy<Value = Self>

Required Methods§

fn arbitrary_with(args: Self::Parameters) -> Self::Strategy

Provided Methods§

fn arbitrary() -> Self::Strategy

Object Safety§

Implementations on Foreign Types§

impl Arbitrary for Ordering

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<Ordering>>), (u32, Arc<Just<Ordering>>), (u32, Arc<Just<Ordering>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for IpAddr

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<MapInto<<Ipv4Addr as Arbitrary>::Strategy, IpAddr>>), (u32, Arc<MapInto<<Ipv6Addr as Arbitrary>::Strategy, IpAddr>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for SocketAddr

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<MapInto<<SocketAddrV4 as Arbitrary>::Strategy, SocketAddr>>), (u32, Arc<MapInto<<SocketAddrV6 as Arbitrary>::Strategy, SocketAddr>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for FpCategory

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<FpCategory>>), (u32, Arc<Just<FpCategory>>), (u32, Arc<Just<FpCategory>>), (u32, Arc<Just<FpCategory>>), (u32, Arc<Just<FpCategory>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for Option<ParseError>

type Parameters = ()

type Strategy = Just<Option<Infallible>>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for Ordering

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<Ordering>>), (u32, Arc<Just<Ordering>>), (u32, Arc<Just<Ordering>>), (u32, Arc<Just<Ordering>>), (u32, Arc<Just<Ordering>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for VarError

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<VarError>>), (u32, Arc<Map<BoxedStrategy<OsString>, fn(_: <BoxedStrategy<OsString> as Strategy>::Value) -> VarError>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for SeekFrom

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Map<<u64 as Arbitrary>::Strategy, fn(_: u64) -> SeekFrom>>), (u32, Arc<Map<<i64 as Arbitrary>::Strategy, fn(_: i64) -> SeekFrom>>), (u32, Arc<Map<<i64 as Arbitrary>::Strategy, fn(_: i64) -> SeekFrom>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for ErrorKind

type Parameters = ()

type Strategy = Union<Just<ErrorKind>>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for Shutdown

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<Shutdown>>), (u32, Arc<Just<Shutdown>>), (u32, Arc<Just<Shutdown>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for RecvTimeoutError

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<RecvTimeoutError>>), (u32, Arc<Just<RecvTimeoutError>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for TryRecvError

type Parameters = ()

type Strategy = TupleUnion<((u32, Arc<Just<TryRecvError>>), (u32, Arc<Just<TryRecvError>>))>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for bool

type Parameters = ()

type Strategy = Any

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for char

type Parameters = ()

type Strategy = CharStrategy<'static>

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for f32

type Parameters = ()

type Strategy = Any

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for f64

type Parameters = ()

type Strategy = Any

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for i8

type Parameters = ()

type Strategy = Any

fn arbitrary_with(_args: Self::Parameters) -> Self::Strategy

impl Arbitrary for i16

type Parameters = ()

Trait Arbitrary