then:
        1 * cancellationHandler.isCancellationRequested() >> false
        1 * workerLease.tryLock() >> true
        1 * workSource.executionState() >> WorkSource.State.MaybeWorkReadyToStart
        1 * workSource.selectNext() >> WorkSource.Selection.of(node)
        1 * worker.execute(node)
        1 * workSource.finishedExecuting(node, null)

        then:
        1 * cancellationHandler.isCancellationRequested() >> false