Waiters

Trait that facilitates performing assertions outside the main test thread, such as assertions in callback methods that are invoked asynchronously.

Trait Waiters provides a Waiter class that you can use to orchestrate the inter-thread communication required to perform assertions outside the main test thread, and a means to configure it.

To use Waiter, create an instance of it in the main test thread:

val w = new Waiter // Do this in the main test thread

At some point later, call await on the waiter:

w.await() // Call await() from the main test thread

The await call will block until it either receives a report of a failed assertion from a different thread, at which point it will complete abruptly with the same exception, or until it is dismissed by a different thread (or threads), at which point it will return normally. You can optionally specify a timeout and/or a number of dismissals to wait for. Here's an example:

import org.scalatest.time.SpanSugar._

w.await(timeout(300 millis), dismissals(2))

The default value for timeout, provided via an implicit PatienceConfig parameter, is 150 milliseconds. The default value for dismissals is 1. The await method will block until either it is dismissed a sufficient number of times by other threads or an assertion fails in another thread. Thus if you just want to perform assertions in just one other thread, only that thread will be performing a dismissal, so you can use the default value of 1 for dismissals.

Waiter contains four overloaded forms of await, two of which take an implicit PatienceConfig parameter. To change the default timeout configuration, override or hide (if you imported the members of Waiters companion object instead of mixing in the trait) patienceConfig with a new one that returns your desired configuration.

To dismiss a waiter, you just invoke dismiss on it:

w.dismiss() // Call this from one or more other threads

You may want to put dismiss invocations in a finally clause to ensure they happen even if an exception is thrown. Otherwise if a dismissal is missed because of a thrown exception, an await call will wait until it times out.

Note that if a Waiter receives more than the expected number of dismissals, it will not report this as an error: i.e., receiving greater than the number of expected dismissals without any failed assertion will simply cause the the test to complete, not to fail. The only way a Waiter will cause a test to fail is if one of the asynchronous assertions to which it is applied fails.

Finally, to perform an assertion in a different thread, you just apply the Waiter to the assertion code. Here are some examples:

w { assert(1 + 1 === 3) }    // Can use assertions
w { 1 + 1 should equal (3) } // Or matchers
w { "hi".charAt(-1) }        // Any exceptions will be forwarded to await

Here's a complete example:

import org.scalatest._
import concurrent.Waiters
import scala.actors.Actor

class ExampleSuite extends FunSuite with Matchers with Waiters {

  case class Message(text: String)

  class Publisher extends Actor {

    @volatile private var handle: Message => Unit = { (msg) => }

    def registerHandler(f: Message => Unit) {
      handle = f
    }

    def act() {
      var done = false
      while (!done) {
        react {
          case msg: Message => handle(msg)
          case "Exit" => done = true
        }
      }
    }
  }

  test("example one") {

    val publisher = new Publisher
    val message = new Message("hi")
    val w = new Waiter

    publisher.start()

    publisher.registerHandler { msg =>
      w { msg should equal (message) }
      w.dismiss()
    }

    publisher ! message
    w.await()
    publisher ! "Exit"
  }
}

Source: Waiters.scala

Linear Supertypes

PatienceConfiguration, AbstractPatienceConfiguration, ScaledTimeSpans, AnyRef, Any

Known Subclasses

Waiters

Type Members

final case class Dismissals(value: Int) extends Product with Serializable

A configuration parameter that specifies the number of dismissals to wait for before returning normally from an await call on a Waiter.
A configuration parameter that specifies the number of dismissals to wait for before returning normally from an await call on a Waiter.
value
the number of dismissals for which to wait

Exceptions thrown
IllegalArgumentException if specified value is less than or equal to zero.
final case class PatienceConfig(timeout: Span = scaled(Span(150, Millis)), interval: Span = scaled(Span(15, Millis))) extends Product with Serializable

Configuration object for asynchronous constructs, such as those provided by traits Eventually and Waiters.
Configuration object for asynchronous constructs, such as those provided by traits Eventually and Waiters.
The default values for the parameters are:

Configuration Parameter Default Value

timeout scaled(150 milliseconds)

interval scaled(15 milliseconds)

timeout
the maximum amount of time to wait for an asynchronous operation to complete before giving up and throwing TestFailedException.
interval
the amount of time to sleep between each check of the status of an asynchronous operation when polling

Definition Classes
AbstractPatienceConfiguration
class Waiter extends AnyRef

Class that facilitates performing assertions outside the main test thread, such as assertions in callback methods that are invoked asynchronously.
Class that facilitates performing assertions outside the main test thread, such as assertions in callback methods that are invoked asynchronously.
To use Waiter, create an instance of it in the main test thread:
```
val w = new Waiter // Do this in the main test thread
```
At some point later, call await on the waiter:
```
w.await() // Call await() from the main test thread
```
The await call will block until it either receives a report of a failed assertion from a different thread, at which point it will complete abruptly with the same exception, or until it is dismissed by a different thread (or threads), at which point it will return normally. You can optionally specify a timeout and/or a number of dismissals to wait for. Here's an example:
```
import org.scalatest.time.SpanSugar._

w.await(timeout(300 millis), dismissals(2))
```
The default value for timeout, provided via an implicit PatienceConfig parameter, is 150 milliseconds. The default value for dismissals is 1. The await method will block until either it is dismissed a sufficient number of times by other threads or an assertion fails in another thread. Thus if you just want to perform assertions in just one other thread, only that thread will be performing a dismissal, so you can use the default value of 1 for dismissals.
Waiter contains four overloaded forms of await, two of which take an implicit PatienceConfig parameter. To change the default timeout configuration, override or hide (if you imported the members of Waiters companion object instead of mixing in the trait) patienceConfig with a new one that returns your desired configuration.
To dismiss a waiter, you just invoke dismiss on it:
```
w.dismiss() // Call this from one or more other threads
```
You may want to put dismiss invocations in a finally clause to ensure they happen even if an exception is thrown. Otherwise if a dismissal is missed because of a thrown exception, an await call will wait until it times out.
Finally, to perform an assertion in a different thread, you just apply the Waiter to the assertion code. Here are some examples:
```
w { assert(1 + 1 === 3) }    // Can use assertions
w { 1 + 1 should equal (3) } // Or matchers
w { "hi".charAt(-1) }        // Any exceptions will be forwarded to await
```
Here's a complete example:
```
import org.scalatest._
import concurrent.Waiters
import scala.actors.Actor

class ExampleSuite extends FunSuite with Matchers with Waiters {

  case class Message(text: String)

  class Publisher extends Actor {

    @volatile private var handle: Message => Unit = { (msg) => }

    def registerHandler(f: Message => Unit) {
      handle = f
    }

    def act() {
      var done = false
      while (!done) {
        react {
          case msg: Message => handle(msg)
          case "Exit" => done = true
        }
      }
    }
  }

  test("example one") {

    val publisher = new Publisher
    val message = new Message("hi")
    val w = new Waiter

    publisher.start()

    publisher.registerHandler { msg =>
      w { msg should equal (message) }
      w.dismiss()
    }

    publisher ! message
    w.await()
    publisher ! "Exit"
  }
}
```

Configuration Parameter	Default Value
`timeout`	`scaled(150 milliseconds)`
`interval`	`scaled(15 milliseconds)`

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
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
def dismissals(value: Int): Dismissals

Returns a Dismissals configuration parameter containing the passed value, which specifies the number of dismissals to wait for before returning normally from an await call on a Waiter.
Returns a Dismissals configuration parameter containing the passed value, which specifies the number of dismissals to wait for before returning normally from an await call on a Waiter.
final def eq(arg0: AnyRef): Boolean

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

Definition Classes
AnyRef → Any
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
def interval(value: Span): Interval

Returns an Interval configuration parameter containing the passed value, which specifies the amount of time to sleep after a retry.
Returns an Interval configuration parameter containing the passed value, which specifies the amount of time to sleep after a retry.

Definition Classes
PatienceConfiguration
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
implicit def patienceConfig: PatienceConfig

Implicit PatienceConfig value providing default configuration values.
Implicit PatienceConfig value providing default configuration values.
To change the default configuration, override or hide this def with another implicit PatienceConfig containing your desired default configuration values.

Definition Classes
PatienceConfiguration → AbstractPatienceConfiguration
final def scaled(span: Span): Span

Scales the passed Span by the Double factor returned by spanScaleFactor.
Scales the passed Span by the Double factor returned by spanScaleFactor.
The Span is scaled by invoking its scaledBy method, thus this method has the same behavior: The value returned by spanScaleFactor can be any positive number or zero, including a fractional number. A number greater than one will scale the Span up to a larger value. A fractional number will scale it down to a smaller value. A factor of 1.0 will cause the exact same Span to be returned. A factor of zero will cause Span.ZeroLength to be returned. If overflow occurs, Span.Max will be returned. If underflow occurs, Span.ZeroLength will be returned.

Definition Classes
ScaledTimeSpans
Exceptions thrown
IllegalArgumentException if the value returned from spanScaleFactor is less than zero
def spanScaleFactor: Double

The factor by which the scaled method will scale Spans.
The factor by which the scaled method will scale Spans.
The default implementation of this method will return the span scale factor that was specified for the run, or 1.0 if no factor was specified. For example, you can specify a span scale factor when invoking ScalaTest via the command line by passing a -F argument to Runner.

Definition Classes
ScaledTimeSpans
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def timeout(value: Span): Timeout

Returns a Timeout configuration parameter containing the passed value, which specifies the maximum amount to wait for an asynchronous operation to complete.
Returns a Timeout configuration parameter containing the passed value, which specifies the maximum amount to wait for an asynchronous operation to complete.

Definition Classes
PatienceConfiguration
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 Docs: object Waiters | package concurrent

trait Waiters extends PatienceConfiguration

Type Members

final case class Dismissals(value: Int) extends Product with Serializable

final case class PatienceConfig(timeout: Span = scaled(Span(150, Millis)), interval: Span = scaled(Span(15, Millis))) extends Product with Serializable

class Waiter extends AnyRef

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

def dismissals(value: Int): Dismissals

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

def interval(value: Span): Interval

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

implicit def patienceConfig: PatienceConfig

final def scaled(span: Span): Span

def spanScaleFactor: Double

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

def timeout(value: Span): Timeout

def toString(): String

final def wait(): Unit

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

final def wait(arg0: Long): Unit

Inherited from PatienceConfiguration

Inherited from AbstractPatienceConfiguration

Inherited from ScaledTimeSpans

Inherited from AnyRef

Inherited from Any

Ungrouped