TestRandom

TestRandom allows for deterministically testing effects involving randomness.

TestRandom operates in two modes. In the first mode, TestRandom is a purely functional pseudo-random number generator. It will generate pseudo-random values just like scala.util.Random except that no internal state is mutated. Instead, methods like nextInt describe state transitions from one random state to another that are automatically composed together through methods like flatMap. The random seed can be set using setSeed and TestRandom is guaranteed to return the same sequence of values for any given seed. This is useful for deterministically generating a sequence of pseudo-random values and powers the property based testing functionality in ZIO Test.

In the second mode, TestRandom maintains an internal buffer of values that can be "fed" with methods such as feedInts and then when random values of that type are generated they will first be taken from the buffer. This is useful for verifying that functions produce the expected output for a given sequence of "random" inputs.

import zio.random._
import zio.test.environment.TestRandom

for {
  _ <- TestRandom.feedInts(4, 5, 2)
  x <- random.nextIntBounded(6)
  y <- random.nextIntBounded(6)
  z <- random.nextIntBounded(6)
} yield x + y + z == 11

TestRandom will automatically take values from the buffer if a value of the appropriate type is available and otherwise generate a pseudo-random value, so there is nothing you need to do to switch between the two modes. Just generate random values as you normally would to get pseudo-random values, or feed in values of your own to get those values back. You can also use methods like clearInts to clear the buffer of values of a given type so you can fill the buffer with new values or go back to pseudo-random number generation.

Linear Supertypes

Serializable, Serializable, AnyRef, Any

Type Members

final case class Buffer(booleans: List[Boolean] = List.empty, bytes: List[Chunk[Byte]] = List.empty, chars: List[Char] = List.empty, doubles: List[Double] = List.empty, floats: List[Float] = List.empty, integers: List[Int] = List.empty, longs: List[Long] = List.empty, strings: List[String] = List.empty, UUIDs: List[UUID] = List.empty) extends Product with Serializable

The buffer of the TestRandom.
final case class Data(seed1: Int, seed2: Int, nextNextGaussians: scala.collection.immutable.Queue[Double] = Queue.empty) extends Product with Serializable

The seed of the TestRandom.
trait Service extends Restorable
final case class Test(randomState: Ref[Data], bufferState: Ref[Buffer]) extends random.Random.Service with Service with Product with Serializable

Adapted from @gzmo work in Scala.js (https://github.com/scala-js/scala-js/pull/780)

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
val DefaultData: Data

An arbitrary initial seed for the TestRandom.
val any: ZLayer[Random with TestRandom, Nothing, Random with TestRandom]
final def asInstanceOf[T0]: T0

Definition Classes
Any
val clearBooleans: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of booleans.
val clearBytes: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of bytes.
val clearChars: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of characters.
val clearDoubles: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of doubles.
val clearFloats: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of floats.
val clearInts: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of integers.
val clearLongs: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of longs.
val clearStrings: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of strings.
val clearUUIDs: URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and clears the buffer of UUIDs.
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
val deterministic: Layer[Nothing, Random with TestRandom]
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def feedBooleans(booleans: Boolean*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of booleans.
def feedBytes(bytes: Chunk[Byte]*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of chunks of bytes.
def feedChars(chars: Char*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of characters.
def feedDoubles(doubles: Double*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of doubles.
def feedFloats(floats: Float*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of floats.
def feedInts(ints: Int*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of integers.
def feedLongs(longs: Long*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of longs.
def feedStrings(strings: String*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of strings.
def feedUUIDs(UUIDs: UUID*): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and feeds the buffer with the specified sequence of UUIDs.
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
val getSeed: URIO[TestRandom, Long]

Accesses a TestRandom instance in the environment and gets the seed.
def hashCode(): Int

Definition Classes
AnyRef → Any
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
def make(data: Data): Layer[Nothing, Random with TestRandom]

Constructs a new TestRandom with the specified initial state.
Constructs a new TestRandom with the specified initial state. This can be useful for providing the required environment to an effect that requires a Random, such as with ZIO#provide.
def makeTest(data: Data): UIO[Test]

Constructs a new Test object that implements the TestRandom interface.
Constructs a new Test object that implements the TestRandom interface. This can be useful for mixing in with implementations of other interfaces.
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
val random: ZLayer[Clock, Nothing, Random with TestRandom]
val save: ZIO[TestRandom, Nothing, UIO[Unit]]

Accesses a TestRandom instance in the environment and saves the random state in an effect which, when run, will restore the TestRandom to the saved state.
def setSeed(seed: ⇒ Long): URIO[TestRandom, Unit]

Accesses a TestRandom instance in the environment and sets the seed to the specified value.
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toString(): String

Definition Classes
AnyRef → Any
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

Related Doc: package environment

object TestRandom extends Serializable

Type Members

final case class Data(seed1: Int, seed2: Int, nextNextGaussians: scala.collection.immutable.Queue[Double] = Queue.empty) extends Product with Serializable

trait Service extends Restorable

final case class Test(randomState: Ref[Data], bufferState: Ref[Buffer]) extends random.Random.Service with Service with Product with Serializable

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

val DefaultData: Data

val any: ZLayer[Random with TestRandom, Nothing, Random with TestRandom]

final def asInstanceOf[T0]: T0

val clearBooleans: URIO[TestRandom, Unit]

val clearBytes: URIO[TestRandom, Unit]

val clearChars: URIO[TestRandom, Unit]

val clearDoubles: URIO[TestRandom, Unit]

val clearFloats: URIO[TestRandom, Unit]

val clearInts: URIO[TestRandom, Unit]

val clearLongs: URIO[TestRandom, Unit]

val clearStrings: URIO[TestRandom, Unit]

val clearUUIDs: URIO[TestRandom, Unit]

def clone(): AnyRef

val deterministic: Layer[Nothing, Random with TestRandom]

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def feedBooleans(booleans: Boolean*): URIO[TestRandom, Unit]

def feedBytes(bytes: Chunk[Byte]*): URIO[TestRandom, Unit]

def feedChars(chars: Char*): URIO[TestRandom, Unit]

def feedDoubles(doubles: Double*): URIO[TestRandom, Unit]

def feedFloats(floats: Float*): URIO[TestRandom, Unit]

def feedInts(ints: Int*): URIO[TestRandom, Unit]

def feedLongs(longs: Long*): URIO[TestRandom, Unit]

def feedStrings(strings: String*): URIO[TestRandom, Unit]

def feedUUIDs(UUIDs: UUID*): URIO[TestRandom, Unit]

def finalize(): Unit

final def getClass(): Class[_]

val getSeed: URIO[TestRandom, Long]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

def make(data: Data): Layer[Nothing, Random with TestRandom]

def makeTest(data: Data): UIO[Test]

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

val random: ZLayer[Clock, Nothing, Random with TestRandom]

val save: ZIO[TestRandom, Nothing, UIO[Unit]]

def setSeed(seed: ⇒ Long): URIO[TestRandom, Unit]

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

Ungrouped