Alexa BDD tests

I am trying to implement BDD test on my Alexa skill. I am using Java SDK to implement it.

Basically, I would like to trigger arbitrary intents programmatically in my test suite and assert on responses, but I could not find any materials to implement it.

All I could find is com.amazon.ask.model.services.skillMessaging.SkillMessagingServiceClient.sendSkillMessage, whose Javadoc says:

Send a message request to a skill for a specified user.

That would be what I need, but, in order to create a com.amazon.ask.model.services.skillMessaging.SkillMessagingServiceClient, I have to do the following:

SkillMessagingServiceClient client = new SkillMessagingServiceClient(
                DefaultApiConfiguration.builder()
                        .withApiClient(ApacheHttpApiClient.standard())
                        .withSerializer(new JacksonSerializer())
                        .withAuthorizationValue("<authorization_token").build(),
                DefaultAuthenticationConfiguration.builder()
                        .withClientId("<client_id>")
                        .withClientSecret("<client_secret>")
                        .build()
        );

In order to get client_id and client_secret:

1. I have accessed Login with Amazon Console
2. I have created a security profile
3. I have enabled Account Linking on my skill, with
   1. Authorization URI: https://www.amazon.com/ap/oa
   2. Access token URI: https://api.amazon.com/auth/o2/token
   3. Client ID and Client secret as from point 2
   4. Scopes: alexa:skill_messaging and profile:user_id
   5. Authentication schema: Basic
4. I have copied all the Alexa Redirect URLs in the allowed return web URIs in my security profile

As a result, now my skill could be bound to my Amazon account from Alexa app, but:

1. All in all, I just wanted to implement tests, NOT bind my account. My skill in production does not need this feature
2. The binding does not work: after confirming it from Alexa app, I receive an error
3. Yet I do not know how to collect the authentication token, unless I catch it from Cloudwatch log and use it... until it expires

At point 2, I could see the reason of the failure: oauthError (https://skills-store.amazon.it/external/link-result?success=false&errorKey=oauth-error&languageCode=it_IT&skillId=amzn1.ask.skill......&skillStage=development). The web page contains a link to RFC6749.

I am currently stuck and I can not test my skill completely, also because it is impossible to test Alexa Player, especially in Italian, unless you directly test it using a physical device.

Thanks for the help.