Struct proptest::test_runner::TestRng

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pub struct TestRng { /* private fields */ }

Expand description

Proptest’s random number generator.

Implementations

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impl TestRng

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pub fn from_seed(algorithm: RngAlgorithm, seed: &[u8]) -> Self

Create a new RNG with the given algorithm and seed.

Any RNG created with the same algorithm-seed pair will produce the same sequence of values on all systems and all supporting versions of proptest.

Panics

Panics if seed is not an appropriate length for algorithm.

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pub fn bytes_used(&self) -> Vec<u8>ⓘNotable traits for Vec<u8, A>`impl<A> Write for Vec<u8, A> where A: Allocator,`

Dumps the bytes obtained from the RNG so far (only works if the RNG is set to Recorder).

Panics

Panics if this RNG does not capture generated data.

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pub fn deterministic_rng(algorithm: RngAlgorithm) -> Self

Returns a TestRng with a particular hard-coded seed.

The seed value will always be the same for a particular version of Proptest and algorithm, but may change across releases.

This is useful for testing things like strategy implementations without risking getting “unlucky” RNGs which deviate from average behaviour enough to cause spurious failures. For example, a strategy for bool which is supposed to produce true 50% of the time might have a test which checks that the distribution is “close enough” to 50%. If every test run starts with a different RNG, occasionally there will be spurious test failures when the RNG happens to produce a very skewed distribution. Using this or TestRunner::deterministic() avoids such issues.

Trait Implementations

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impl Clone for TestRng

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fn clone(&self) -> TestRng

Returns a copy of the value. Read more

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

Performs copy-assignment from source. Read more

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impl Debug for TestRng

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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impl RngCore for TestRng

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fn next_u32(&mut self) -> u32

Return the next random u32. Read more

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fn next_u64(&mut self) -> u64

Return the next random u64. Read more

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fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data. Read more

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fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill dest entirely with random data. Read more

Auto Trait Implementations

impl RefUnwindSafe for TestRng

impl Send for TestRng

impl Sync for TestRng

impl Unpin for TestRng

impl UnwindSafe for TestRng

Blanket Implementations

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impl<T> Any for T where
T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

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impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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impl<T> From<T> for T

const: unstable · source

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into for T where
U: From<T>,

const: unstable · source

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<R> Rng for R where
R: RngCore + ?Sized,

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fn gen<T>(&mut self) -> T where
Standard: Distribution<T>,

Return a random value supporting the Standard distribution. Read more

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fn gen_range<T, R>(&mut self, range: R) -> T where
T: SampleUniform,
R: SampleRange<T>,

Generate a random value in the given range. Read more

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fn sample<T, D>(&mut self, distr: D) -> T where
D: Distribution<T>,

Sample a new value, using the given distribution. Read more

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fn sample_iter<T, D>(self, distr: D) -> DistIter<D, Self, T> where
D: Distribution<T>,

Create an iterator that generates values using the given distribution. Read more

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fn fill<T>(&mut self, dest: &mut T) where
T: Fill + ?Sized,

Fill any type implementing Fill with random data Read more

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fn try_fill<T>(&mut self, dest: &mut T) -> Result<(), Error> where
T: Fill + ?Sized,

Fill any type implementing Fill with random data Read more

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fn gen_bool(&mut self, p: f64) -> bool

Return a bool with a probability p of being true. Read more

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fn gen_ratio(&mut self, numerator: u32, denominator: u32) -> bool

Return a bool with a probability of numerator/denominator of being true. I.e. gen_ratio(2, 3) has chance of 2 in 3, or about 67%, of returning true. If numerator == denominator, then the returned value is guaranteed to be true. If numerator == 0, then the returned value is guaranteed to be false. Read more

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impl<T> ToOwned for T where
T: Clone,

type Owned = T

The resulting type after obtaining ownership.

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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more

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impl<T, U> TryFrom for T where
U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

fn try_from(value: U) -> Result<T, <T as TryFrom>::Error>

Performs the conversion.

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impl<T, U> TryInto for T where
U: TryFrom<T>,

type Error = >::Error

The type returned in the event of a conversion error.

const: unstable · source

fn try_into(self) -> Result<U, >::Error>

Performs the conversion.

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impl<V, T> VZip<V> for T where
V: MultiLane<T>,

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Struct proptest::test_runner::TestRng

Implementations

impl TestRng

pub fn from_seed(algorithm: RngAlgorithm, seed: &[u8]) -> Self

pub fn bytes_used(&self) -> Vec<u8>ⓘNotable traits for Vec<u8, A>impl<A> Write for Vec<u8, A> where A: Allocator,

pub fn deterministic_rng(algorithm: RngAlgorithm) -> Self

Trait Implementations

impl Clone for TestRng

fn clone(&self) -> TestRng

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

impl Debug for TestRng

fn fmt(&self, f: &mut Formatter<'_>) -> Result

impl RngCore for TestRng

fn next_u32(&mut self) -> u32

fn next_u64(&mut self) -> u64

fn fill_bytes(&mut self, dest: &mut [u8])

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Auto Trait Implementations

impl RefUnwindSafe for TestRng

impl Send for TestRng

impl Sync for TestRng

impl Unpin for TestRng

impl UnwindSafe for TestRng

Blanket Implementations

impl<T> Any for T where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

impl<T> Borrow<T> for T where T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for T where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

impl<T> From<T> for T

fn from(t: T) -> T

impl<T, U> Into<U> for T where U: From<T>,

fn into(self) -> U

impl<R> Rng for R where R: RngCore + ?Sized,

fn gen<T>(&mut self) -> T where Standard: Distribution<T>,

fn gen_range<T, R>(&mut self, range: R) -> T where T: SampleUniform, R: SampleRange<T>,

fn sample<T, D>(&mut self, distr: D) -> T where D: Distribution<T>,

fn sample_iter<T, D>(self, distr: D) -> DistIter<D, Self, T> where D: Distribution<T>,

fn fill<T>(&mut self, dest: &mut T) where T: Fill + ?Sized,

fn try_fill<T>(&mut self, dest: &mut T) -> Result<(), Error> where T: Fill + ?Sized,

fn gen_bool(&mut self, p: f64) -> bool

fn gen_ratio(&mut self, numerator: u32, denominator: u32) -> bool

impl<T> ToOwned for T where T: Clone,

type Owned = T

fn to_owned(&self) -> T

fn clone_into(&self, target: &mut T)

impl<T, U> TryFrom<U> for T where U: Into<T>,

type Error = Infallible

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

impl<T, U> TryInto<U> for T where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

impl<V, T> VZip<V> for T where V: MultiLane<T>,

fn vzip(self) -> V

pub fn bytes_used(&self) -> Vec<u8>ⓘNotable traits for Vec<u8, A>`impl<A> Write for Vec<u8, A> where A: Allocator,`

impl<T> Any for T where
T: 'static + ?Sized,

impl<T> Borrow<T> for T where
T: ?Sized,

impl<T> BorrowMut<T> for T where
T: ?Sized,

impl<T, U> Into<U> for T where
U: From<T>,

impl<R> Rng for R where
R: RngCore + ?Sized,

fn gen<T>(&mut self) -> T where
Standard: Distribution<T>,

fn gen_range<T, R>(&mut self, range: R) -> T where
T: SampleUniform,
R: SampleRange<T>,

fn sample<T, D>(&mut self, distr: D) -> T where
D: Distribution<T>,

fn sample_iter<T, D>(self, distr: D) -> DistIter<D, Self, T> where
D: Distribution<T>,

fn fill<T>(&mut self, dest: &mut T) where
T: Fill + ?Sized,

fn try_fill<T>(&mut self, dest: &mut T) -> Result<(), Error> where
T: Fill + ?Sized,

impl<T> ToOwned for T where
T: Clone,

impl<T, U> TryFrom<U> for T where
U: Into<T>,

impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

impl<V, T> VZip<V> for T where
V: MultiLane<T>,