TestClock

TestClock makes it easy to deterministically and efficiently test effects involving the passage of time.

Instead of waiting for actual time to pass, sleep and methods implemented in terms of it schedule effects to take place at a given wall clock time. Users can adjust the wall clock time using the adjust and setTime methods, and all effects scheduled to take place on or before that wall clock time will automically be run.

For example, here is how we can test ZIO#timeout using TestClock:

import zio.ZIO
import zio.duration._
import zio.test.environment.TestClock

for {
  fiber  <- ZIO.sleep(5.minutes).timeout(1.minute).fork
  _      <- TestClock.adjust(1.minute)
  result <- fiber.join
} yield result == None

Note how we forked the fiber that sleep was invoked on. Calls to sleep and methods derived from it will semantically block until the wall clock time is set to on or after the time they are scheduled to run. If we didn't fork the fiber on which we called sleep we would never get to set the the wall clock time on the line below. Thus, a useful pattern when using TestClock is to fork the effect being tested, then adjust the wall clock time, and finally verify that the expected effects have been performed.

Sleep and related combinators schedule events to occur at a specified duration in the future relative to the current fiber time (e.g. 10 seconds from the current fiber time). The fiber time is backed by a FiberRef and is incremented for the duration each fiber is sleeping. Child fibers inherit the fiber time of their parent so methods that rely on repeated sleep calls work as you would expect.

For example, here is how we can test an effect that recurs with a fixed delay:

import zio.Queue
import zio.duration._
import zio.test.environment.TestClock

for {
  q <- Queue.unbounded[Unit]
  _ <- (q.offer(()).delay(60.minutes)).forever.fork
  a <- q.poll.map(_.isEmpty)
  _ <- TestClock.adjust(60.minutes)
  b <- q.take.as(true)
  c <- q.poll.map(_.isEmpty)
  _ <- TestClock.adjust(60.minutes)
  d <- q.take.as(true)
  e <- q.poll.map(_.isEmpty)
} yield a && b && c && d && e

Here we verify that no effect is performed before the recurrence period, that an effect is performed after the recurrence period, and that the effect is performed exactly once. The key thing to note here is that after each recurrence the next recurrence is scheduled to occur at the appropriate time in the future, so when we adjust the wall clock time by 60 minutes exactly one value is placed in the queue, and when we adjust the wall clock time by another 60 minutes exactly one more value is placed in the queue.

Linear Supertypes

Serializable, Serializable, AnyRef, Any

Type Members

final case class Data(duration: Duration, sleeps: List[(Duration, Promise[Nothing, Unit])]) extends Product with Serializable

The state of the TestClock.
final case class FiberData(duration: Duration, timeZone: ZoneId) extends Product with Serializable
trait Service extends Restorable
final case class Test(clockState: Ref[Data], fiberState: FiberRef[FiberData], live: Live.Service, warningState: RefM[WarningData]) extends clock.Clock.Service with Service with Product with Serializable
sealed trait WarningData extends AnyRef

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
object FiberData extends Serializable
object WarningData
def adjust(duration: ⇒ Duration): ZIO[TestClock, Nothing, Unit]

Accesses a TestClock instance in the environment and increments the wall clock time by the specified duration, running any actions scheduled for on or before the new time.
val any: ZLayer[Clock with TestClock, Nothing, Clock with TestClock]
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
val default: ZLayer[Live, Nothing, Clock with TestClock]
final def eq(arg0: AnyRef): Boolean

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

Definition Classes
AnyRef → Any
val fiberTime: ZIO[TestClock, Nothing, Duration]

Accesses a TestClock instance in the environment and returns the current fiber time for this fiber.
def finalize(): Unit

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

Definition Classes
AnyRef → Any
def hashCode(): Int

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

Definition Classes
Any
def live(data: Data): ZLayer[Live, Nothing, Clock with TestClock]

Constructs a new Test object that implements the TestClock interface.
Constructs a new Test object that implements the TestClock 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 runAll: ZIO[TestClock, Nothing, Unit]

Accesses a TestClock instance in the environment and runs all scheduled effects.
Accesses a TestClock instance in the environment and runs all scheduled effects. After this any scheduled effects will be run immediately.
val save: ZIO[TestClock, Nothing, UIO[Unit]]

Accesses a TestClock instance in the environment and saves the clock state in an effect which, when run, will restore the TestClock to the saved state
def setDateTime(dateTime: ⇒ OffsetDateTime): ZIO[TestClock, Nothing, Unit]

Accesses a TestClock instance in the environment and sets the wall clock time to the specified OffsetDateTime, running any actions scheduled for on or before the new time.
def setTime(duration: ⇒ Duration): ZIO[TestClock, Nothing, Unit]

Accesses a TestClock instance in the environment and sets the wall clock time to the specified time in terms of duration since the epoch, running any actions scheduled for on or before the new time.
def setTimeZone(zone: ⇒ ZoneId): ZIO[TestClock, Nothing, Unit]

Accesses a TestClock instance in the environment, setting the time zone to the specified time zone.
Accesses a TestClock instance in the environment, setting the time zone to the specified time zone. The wall clock time in terms of nanoseconds since the epoch will not be altered and no scheduled actions will be run as a result of this effect.
val sleeps: ZIO[TestClock, Nothing, List[Duration]]

Accesses a TestClock instance in the environment and returns a list of wall clock times that effects are scheduled to run.
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
val timeZone: ZIO[TestClock, Nothing, ZoneId]

Accesses a TestClock instance in the environment and returns the current time zone.
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 TestClock extends Serializable

Type Members

final case class Data(duration: Duration, sleeps: List[(Duration, Promise[Nothing, Unit])]) extends Product with Serializable

final case class FiberData(duration: Duration, timeZone: ZoneId) extends Product with Serializable

trait Service extends Restorable

final case class Test(clockState: Ref[Data], fiberState: FiberRef[FiberData], live: Live.Service, warningState: RefM[WarningData]) extends clock.Clock.Service with Service with Product with Serializable

sealed trait WarningData extends AnyRef

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

object FiberData extends Serializable

object WarningData

def adjust(duration: ⇒ Duration): ZIO[TestClock, Nothing, Unit]

val any: ZLayer[Clock with TestClock, Nothing, Clock with TestClock]

final def asInstanceOf[T0]: T0

def clone(): AnyRef

val default: ZLayer[Live, Nothing, Clock with TestClock]

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

val fiberTime: ZIO[TestClock, Nothing, Duration]

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

def live(data: Data): ZLayer[Live, Nothing, Clock with TestClock]

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

val runAll: ZIO[TestClock, Nothing, Unit]

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

def setDateTime(dateTime: ⇒ OffsetDateTime): ZIO[TestClock, Nothing, Unit]

def setTime(duration: ⇒ Duration): ZIO[TestClock, Nothing, Unit]

def setTimeZone(zone: ⇒ ZoneId): ZIO[TestClock, Nothing, Unit]

val sleeps: ZIO[TestClock, Nothing, List[Duration]]

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

val timeZone: ZIO[TestClock, Nothing, ZoneId]

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