Struct proptest::strategy::LazyJust

pub struct LazyJust<T, F: Fn() -> T> { /* fields omitted */ }

A Strategy which always produces a single value value and never simplifies. If T is Clone, you should use Just instead.

This is a generalization of Just and works by calling the provided Fn() -> T in .current() every time. This is not a very interesting strategy, but is required in cases where T is not Clone. It is also used in proptest_derive where we can't assume that your type is Clone.

It is important that the function used be pure.

Methods

impl<T, F: Fn() -> T> LazyJust<T, F>

pub fn new(function: F) -> Self

Constructs a LazyJust strategy given the function/closure that produces the value.

It is important that the function used be pure.

Trait Implementations

impl<T: Debug, F: Clone + Fn() -> T> Strategy for LazyJust<T, F>

type Value = Self

The value tree generated by this Strategy.

fn new_value(&self, _: &mut TestRunner) -> NewTree<Self>

Generate a new value tree from the given runner.

fn prop_map<O: Debug, F: Fn(ValueFor<Self>) -> O>(self, fun: F) -> Map<Self, F> where
    Self: Sized, 

Returns a strategy which produces values transformed by the function fun.

fn prop_map_into<O: Debug>(self) -> MapInto<Self, O> where
    Self: Sized,
    ValueFor<Self>: Into<O>, 

Returns a strategy which produces values of type O by transforming Self with Into<O>.

fn prop_perturb<O: Debug, F: Fn(ValueFor<Self>, XorShiftRng) -> O>(
    self,
    fun: F
) -> Perturb<Self, F> where
    Self: Sized, 

Returns a strategy which produces values transformed by the function fun, which is additionally given a random number generator.

fn prop_flat_map<S: Strategy, F: Fn(ValueFor<Self>) -> S>(
    self,
    fun: F
) -> Flatten<Map<Self, F>> where
    Self: Sized, 

Maps values produced by this strategy into new strategies and picks values from those strategies.

fn prop_ind_flat_map<S: Strategy, F: Fn(ValueFor<Self>) -> S>(
    self,
    fun: F
) -> IndFlatten<Map<Self, F>> where
    Self: Sized, 

Maps values produced by this strategy into new strategies and picks values from those strategies while considering the new strategies to be independent.

fn prop_ind_flat_map2<S: Strategy, F: Fn(ValueFor<Self>) -> S>(
    self,
    fun: F
) -> IndFlattenMap<Self, F> where
    Self: Sized, 

Similar to prop_ind_flat_map(), but produces 2-tuples with the input generated from self in slot 0 and the derived strategy in slot 1.

fn prop_filter<R: Into<Reason>, F: Fn(&ValueFor<Self>) -> bool>(
    self,
    whence: R,
    fun: F
) -> Filter<Self, F> where
    Self: Sized, 

Returns a strategy which only produces values accepted by fun.

fn prop_union(self, other: Self) -> Union<Self> where
    Self: Sized, 

Returns a strategy which picks uniformly from self and other.

fn prop_recursive<R, F>(
    self,
    depth: u32,
    desired_size: u32,
    expected_branch_size: u32,
    recurse: F
) -> Recursive<ValueFor<Self>, F> where
    Self: Sized + 'static,
    F: Fn(BoxedStrategy<ValueFor<Self>>) -> R,
    R: Strategy + 'static,
    R::Value: ValueTree<Value = ValueFor<Self>>, 

Generate a recursive structure with self items as leaves.

fn prop_shuffle(self) -> Shuffle<Self> where
    Self: Sized,
    ValueFor<Self>: Shuffleable, 

Shuffle the contents of the values produced by this strategy.

fn boxed(self) -> BoxedStrategy<ValueFor<Self>> where
    Self: Sized + 'static, 

Erases the type of this Strategy so it can be passed around as a simple trait object.

fn sboxed(self) -> SBoxedStrategy<ValueFor<Self>> where
    Self: Sized + Send + Sync + 'static, 

Erases the type of this Strategy so it can be passed around as a simple trait object.

fn no_shrink(self) -> NoShrink<Self> where
    Self: Sized, 

Wraps this strategy to prevent values from being subject to shrinking.

impl<T: Debug, F: Fn() -> T> ValueTree for LazyJust<T, F>

type Value = T

The type of the value produced by this ValueTree.

fn simplify(&mut self) -> bool

Attempts to simplify the current value. Notionally, this sets the "high" value to the current value, and the current value to a "halfway point" between high and low, rounding towards low.

fn complicate(&mut self) -> bool

Attempts to partially undo the last simplification. Notionally, this sets the "low" value to one plus the current value, and the current value to a "halfway point" between high and the new low, rounding towards low.

fn current(&self) -> Self::Value

Returns the current value.

impl<T, F: Copy + Fn() -> T> Copy for LazyJust<T, F>

impl<T, F: Clone + Fn() -> T> Clone for LazyJust<T, F>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T, F: Fn() -> T> Debug for LazyJust<T, F>

fn fmt(&self, fmt: &mut Formatter) -> Result

Formats the value using the given formatter.