creating_a_seam_books_approach.kt

class TestingTaskChecker : TaskChecker() {
    override fun sendTaskToAssigner(task: Task) {
        //  do nothing
    }
}

open class TaskChecker {

    fun check(task: Task): CheckResult {

        if (isNotCreatedInCurrentWeek(task)) return Invalid
        if (isResolved(task)) return Invalid
        if (isNotAssigned(task)) return Invalid

        return Valid
    }

    private fun isNotAssigned(task: Task): Boolean {
        if (task.assignedTo != Nobody) return false

        sendTaskToAssigner(task)

        return true
    }

    protected open fun sendTaskToAssigner(task: Task) {
        val connection = Connection()
        val assigner = TaskAssigner(connection)
        assigner.add(task)
    }

    //...
}