Play Framework/Scala example source code file (TestExecutionContext.scala)

This example Play Framework source code file (TestExecutionContext.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Play Framework (and Scala) source code examples by using tags.

All credit for the original source code belongs to Play Framework; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Play Framework tags/keywords

a, api, can, cannot, concurrent, executioncontext, int, iterate, library, play, play framework, runnable, runtimeexception, testexecutioncontext, throwable, unit

The TestExecutionContext.scala Play Framework example source code

/*
 * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
 */
package play.api.libs.iteratee

import scala.concurrent.ExecutionContext

object TestExecutionContext {
  
  /**
   * Create a `TestExecutionContext` that delegates to the iteratee package's default `ExecutionContext`.
   */
  def apply(): TestExecutionContext = new TestExecutionContext(Execution.defaultExecutionContext)

}

/**
 * An `ExecutionContext` that counts its executions.
 * 
 * @param delegate The underlying `ExecutionContext` to delegate execution to.
 */
class TestExecutionContext(delegate: ExecutionContext) extends ExecutionContext {
  top =>

  val count = new java.util.concurrent.atomic.AtomicInteger()

  val local = new ThreadLocal[java.lang.Boolean]
  
  def preparable[A](body: => A): A = {
    local.set(true)
    try body finally local.set(null)
  }

  def execute(runnable: Runnable): Unit = {
    throw new RuntimeException("Cannot execute unprepared TestExecutionContext")
  }
  
  def reportFailure(t: Throwable): Unit = delegate.reportFailure(t)
  
  override def prepare(): ExecutionContext = {
    val isLocal = Option(local.get()).getOrElse(false: java.lang.Boolean)
    if (!isLocal) throw new RuntimeException("Can only prepare TestExecutionContext within 'preparable' scope")
    val preparedDelegate = delegate.prepare()
    return new ExecutionContext {

      def execute(runnable: Runnable): Unit = {
	    count.getAndIncrement()
	    preparedDelegate.execute(runnable)
	  }
	  
	  def reportFailure(t: Throwable): Unit = preparedDelegate.reportFailure(t)
      
    }
  }
  
  def executionCount: Int = count.get()
  
}