Fix newsletter subscriptions between stores

[sbaixauli]

Include store_id in query result in order to ensure that the action (subscribe/unsubscribe) it’s done in the correct store.

Description

When user have different accounts in two or more stores newsletter table save the subscription status, store_id and customer_id.
The problem is that when we try to update this information the query result don't keep in mind the store of the user.

Fixed Issues (if relevant)

1. Newsletter subscriptions status not isolated between multi stores #10014: Newsletter subscriptions status not isolated between multi stores

Manual testing scenarios

1. Create user: 'me@domain.com' in the first store (Website 1). Subscribe it to general subscription list.
2. Login this user 'me@domain.com' in the second store (Website 2). Subscribe it to general subscription list.
3. Login in the second store and uncheck subscription list.
4. Logout and login the user in the first store. The user mantain the subscription.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.

[dmanners]

The updating for the data seems to be fine but I noticed during testing with 2 store views that the frontend will not load the right information.

Using the following steps.

1. Create system with 2 store views,
2. Create account and register for newsletter on 1 store view,
3. Switch store view and see You are subscribed to "General Subscription". even though admin shows you are not registered.

[dmanners]

@sbaixauli I updated the unit and integration tests so hopefully it all passes now.

1. Unit tests failed as they could not mock the new call to the store manager. 19fe0df
2. Integration tests failed as the customer created via dev/tests/integration/testsuite/Magento/Customer/_files/two_customers.php was attached to one store but the subscriber created via dev/tests/integration/testsuite/Magento/Newsletter/_files/subscribers.php ended up being attached to a different store. dev/tests/integration/testsuite/Magento/Newsletter/_files/subscribers.php

Hopefully this passes and we can now continue with the processing of this PR.

[dmanners]

@sbaixauli if you are interested in knowing I used http://devdocs.magento.com/guides/v2.2/test/integration/integration_test_execution.html to run the individual tests that had been failing. Then stepped through the process using xdebug. I noticed that the stores did not match, which previously did not matter but with your change now mattered, so I updated the test fixtures to match.

[sbaixauli]

Thanks for all @dmanners!

[Nil79]

Hello @sbaixauli , due to the issue that I reported in my pull request #13469 , I was checking the function loadByCustomerId in Magento/Newsletter/Model/Subscriber.php.

I noticed that also removing the line that you added ($customerData->setStoreId($this->_storeManager->getStore()->getId());), the newsletter subscription is working fine on frontend in a multi site scenario.

I don't know if my checks are right, can you please give me a feedback? Thanks.