def failure = new RuntimeException()
        def brokenListener = Mock(OperationCompletionListener)
        def okListener = Mock(OperationCompletionListener)

        when:
        registry.onTaskCompletion(Providers.of(brokenListener))
        registry.onTaskCompletion(Providers.of(okListener))
        async {
            factory.fire(taskFinishEvent())

        buildFile << """
            class BrokenListener implements StandardOutputListener {
                void onOutput(CharSequence output) {
                    throw new RuntimeException("broken")
                }
            }
            def output = new BrokenListener()
            def error = new BrokenListener()

            task brokenOut {
                doLast {