[][src]Struct proptest::test_runner::TestRng

pub struct TestRng { /* fields omitted */ }

Proptest's random number generator.


impl TestRng[src]

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

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 if seed is not an appropriate length for algorithm.

pub fn bytes_used(&self) -> Vec<u8>

Notable traits for Vec<u8, Global>

impl Write for Vec<u8, Global>

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


Panics if this RNG does not capture generated data.

pub fn deterministic_rng(algorithm: RngAlgorithm) -> Self[src]

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 Clone for TestRng[src]

impl Debug for TestRng[src]

impl RngCore for TestRng[src]

Auto Trait Implementations

impl RefUnwindSafe for TestRng[src]

impl Send for TestRng[src]

impl Sync for TestRng[src]

impl Unpin for TestRng[src]

impl UnwindSafe for TestRng[src]

Blanket Implementations

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> From<T> for T[src]

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

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

impl<T> ToOwned for T where
    T: Clone

type Owned = T

The resulting type after obtaining ownership.

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

type Error = Infallible

The type returned in the event of a conversion error.

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

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

The type returned in the event of a conversion error.

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