Replacing Dependencies For Better Testability

When it comes to handling the time, no one wants to wait for 30 minutes for a scheduler job, or for a delayed task to be able to test it. In these situations what we need to do is advancing the time, or replacing the effect of the time for our needs. This may require you to change your code, too. Because, we might need to provide a time-free implementation to an interface, or we might need to extract it to an interface if not properly implemented.

For example, in international-service project we have a delayed command executor that accepts a task and a time for it to delay it until it is right time to execute. But, in tests we need to replace this behaviour with the time-effect free implementation.

class BackgroundCommandBusImpl // is the class for delayed operations

We would like to by-pass the time-bounded logic inside BackgroundCommandBusImpl, and for e2eTest scope we write:

class NoDelayBackgroundCommandBusImpl(
    backgroundMessageEnvelopeDispatcher: BackgroundMessageEnvelopeDispatcher,
    backgroundMessageEnvelopeStorage: BackgroundMessageEnvelopeStorage,
    lockProvider: CouchbaseLockProvider,
) : BackgroundCommandBusImpl(
    backgroundMessageEnvelopeDispatcher,
    backgroundMessageEnvelopeStorage,
    lockProvider
) {

    override suspend fun <TNotification : BackgroundNotification> publish(
        notification: TNotification,
        options: BackgroundOptions,
    ) {
        super.publish(notification, options.withDelay(0))
    }

    override suspend fun <TCommand : BackgroundCommand> send(
        command: TCommand,
        options: BackgroundOptions,
    ) {
        super.send(command, options.withDelay(0))
    }
}

Now, it is time to tell to e2eTest system to use NoDelay implementation.

That brings us to initializers.