Recently I have taken a bit of a detour into the world of telephony, working with Asterisk-Java, which by itself is a very valuable tool, and worth knowing a bit about if you are integrating a system with Asterisk. While it is a Java-based library, I am integrating it into a Grails application.

We have a fairly comprehensive suite of unit tests asserting that desired behaviors are triggered upon certain events initiated through the Event API. This is made even easier, as usual, with Groovy– specifically on the testing front. Here I show two hypothetical test cases, followed by supporting code that works specifically with the Asterisk-Java classes…

import org.gmock.GMockTestCase
import org.asteriskjava.manager.event.JoinEvent
import org.asteriskjava.manager.event.LeaveEvent

def queueObject = // .... some object representing an internal queue

/*
 * Verifies caller entering a call queue will trigger behavior
 */
void testCallIAddedToQueue() {
  mock(queueObject).add('SIP/123', '3125551234').once()
  dispatchJoinEvent([channel: "SIP/123", callerId: "3125551234"])
}

/*
 * Verifies caller leaving call queue will trigger behavior
 */
void testCallRemovedFromQueue() {
    mock(queueObject).remove("SIP/123").once()
    dispatchLeaveEvent([channel: "SIP/123", dateReceived: new Date()])
}
// ...

The testcases above are fairly straightforward, hiding much of the details involved when working with Asterisk-Java. The ‘queueObject’ can be anything, really, as long as it contains behavior which we wired into the event-handling system Asterisk-Java provides. The important part here is how we can easily bind properties to the underlying Event types, and dispatch them so that our behavior is invoked.

private def dispatchJoinEvent(properties) {
  dispatchEvent(JoinEvent, properties)
}

private def dispatchLeaveEvent(properties) {
  dispatchEvent(LeaveEvent, properties)
}

private def dispatchEvent(eventType, eventProperties) {
  def event = eventType.newInstance([:])
  eventProperties.each { name, value -> event."${name}" = value }
  play {
    asteriskService.connection.dispatchEvent(event)
  }
}

Here I have a ‘service’ class defined in Grails which I call ‘asteriskService’. It encapsulates access to the Asterisk-Java ManagerConnection instance, which in turn can dispatch specific events.

Of interest to those new with Groovy is the binding of properties within ‘dispatchEvent()’. It looks perhaps a bit more complex than one would hope, but unfortunately JoinEvent and LeaveEvent do not have default constructors, requiring the code to ‘new’ them up with a placeholder argument, and then set any properties on the fly.

Asterisk-Java is worth checking out, but particularly nice is using a bit of Groovy to tie it in nicely. While this can benefit the application, you can see how it helps ease testing– particularly as you start using more and more of what the library offers.

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