org.scalatest.concurrent

AsyncAssertions

trait AsyncAssertions extends PatienceConfiguration

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

Trait AsyncAssertions 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 AsyncAssertions 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.AsyncAssertions
import matchers.ShouldMatchers
import scala.actors.Actor

class ExampleSuite extends FunSuite with ShouldMatchers with AsyncAssertions {

  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"
  }
}

Linear Supertypes
PatienceConfiguration, AbstractPatienceConfiguration, ScaledTimeSpans, AnyRef, Any
Known Subclasses
AsyncAssertions
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Type Members

  1. 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.

  2. case class Interval (value: Span) extends PatienceConfigParam with Product with Serializable

    A PatienceConfigParam that specifies the amount of time to sleep after a retry.

  3. case class PatienceConfig (timeout: Span, interval: Span) extends Product with Serializable

    Configuration object for asynchronous constructs, such as those provided by traits Eventually and AsyncAssertions.

  4. class PatienceConfigParam extends AnyRef

    Abstract class defining a family of configuration parameters for traits Eventually and AsyncAssertions.

  5. case class Timeout (value: Span) extends PatienceConfigParam with Product with Serializable

    A PatienceConfigParam that specifies the maximum amount of time to wait for an asynchronous operation to complete.

  6. class Waiter extends AnyRef

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

Value Members

  1. def != (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef

  2. def != (arg0: Any): Boolean

    Attributes
    final
    Definition Classes
    Any

  3. def ## (): Int

    Attributes
    final
    Definition Classes
    AnyRef → Any

  4. def == (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef

  5. def == (arg0: Any): Boolean

    Attributes
    final
    Definition Classes
    Any

  6. def asInstanceOf [T0] : T0

    Attributes
    final
    Definition Classes
    Any

  7. def clone (): AnyRef

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()

  8. 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.

  9. def eq (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef

  10. def equals (arg0: Any): Boolean

    Definition Classes
    AnyRef → Any

  11. def finalize (): Unit

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()

  12. def getClass (): java.lang.Class[_]

    Attributes
    final
    Definition Classes
    AnyRef

  13. def hashCode (): Int

    Definition Classes
    AnyRef → Any

  14. 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

  15. def isInstanceOf [T0] : Boolean

    Attributes
    final
    Definition Classes
    Any

  16. def ne (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef

  17. def notify (): Unit

    Attributes
    final
    Definition Classes
    AnyRef

  18. def notifyAll (): Unit

    Attributes
    final
    Definition Classes
    AnyRef

  19. 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.

    Attributes
    implicit
    Definition Classes
    PatienceConfiguration → AbstractPatienceConfiguration

  20. 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.

    Attributes
    final
    Definition Classes
    ScaledTimeSpans

  21. 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

  22. def synchronized [T0] (arg0: ⇒ T0): T0

    Attributes
    final
    Definition Classes
    AnyRef

  23. 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

  24. def toString (): String

    Definition Classes
    AnyRef → Any

  25. def wait (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()

  26. def wait (arg0: Long, arg1: Int): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()

  27. def wait (arg0: Long): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()

Inherited from PatienceConfiguration

Inherited from AbstractPatienceConfiguration

Inherited from ScaledTimeSpans

Inherited from AnyRef

Inherited from Any