[−][src]Struct proptest::test_runner::TestRng
Proptest's random number generator.
Methods
impl TestRng
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pub fn from_seed(algorithm: RngAlgorithm, seed: &[u8]) -> Self
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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
.
pub fn deterministic_rng(algorithm: RngAlgorithm) -> Self
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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
impl Debug for TestRng
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impl Clone for TestRng
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fn clone(&self) -> TestRng
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fn clone_from(&mut self, source: &Self)
1.0.0[src]
Performs copy-assignment from source
. Read more
impl RngCore for TestRng
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Auto Trait Implementations
Blanket Implementations
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> From<T> for T
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<R> Rng for R where
R: RngCore + ?Sized,
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R: RngCore + ?Sized,
fn gen<T>(&mut self) -> T where
Standard: Distribution<T>,
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Standard: Distribution<T>,
Return a random value supporting the [Standard
] distribution. Read more
fn gen_range<T, B1, B2>(&mut self, low: B1, high: B2) -> T where
B1: SampleBorrow<T>,
B2: SampleBorrow<T>,
T: SampleUniform,
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B1: SampleBorrow<T>,
B2: SampleBorrow<T>,
T: SampleUniform,
Generate a random value in the range [low
, high
), i.e. inclusive of low
and exclusive of high
. Read more
fn sample<T, D>(&mut self, distr: D) -> T where
D: Distribution<T>,
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D: Distribution<T>,
Sample a new value, using the given distribution. Read more
fn sample_iter<T, D>(&'a mut self, distr: &'a D) -> DistIter<'a, D, Self, T> where
D: Distribution<T>,
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D: Distribution<T>,
Create an iterator that generates values using the given distribution. Read more
fn fill<T>(&mut self, dest: &mut T) where
T: AsByteSliceMut + ?Sized,
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T: AsByteSliceMut + ?Sized,
Fill dest
entirely with random bytes (uniform value distribution), where dest
is any type supporting [AsByteSliceMut
], namely slices and arrays over primitive integer types (i8
, i16
, u32
, etc.). Read more
fn try_fill<T>(&mut self, dest: &mut T) -> Result<(), Error> where
T: AsByteSliceMut + ?Sized,
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T: AsByteSliceMut + ?Sized,
Fill dest
entirely with random bytes (uniform value distribution), where dest
is any type supporting [AsByteSliceMut
], namely slices and arrays over primitive integer types (i8
, i16
, u32
, etc.). Read more
fn gen_bool(&mut self, p: f64) -> bool
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Return a bool with a probability p
of being true. Read more
fn gen_ratio(&mut self, numerator: u32, denominator: u32) -> bool
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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
fn choose<T>(&mut self, values: &'a [T]) -> Option<&'a T>
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use SliceRandom::choose instead
Return a random element from values
. Read more
fn choose_mut<T>(&mut self, values: &'a mut [T]) -> Option<&'a mut T>
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use SliceRandom::choose_mut instead
Return a mutable pointer to a random element from values
. Read more
fn shuffle<T>(&mut self, values: &mut [T])
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use SliceRandom::shuffle instead
Shuffle a mutable slice in place. Read more