'Allowed Countries' - get countries for scope 'default'.

[swnsma]

Description

• fix 'if' for scope with id 0;
• add test for this case;

Fixed Issues

1. magento/magento2#?: Not found relevant issue for the problem

Manual testing scenarios

Pre-conditions

1. Installation with website - Website and tore - Store.
2. Configured different 'Allowed Countries' for 'Default' and Store scopes.

Steps To Reproduce

1. Require Magento\Directory\Model\AllowedCountries class
2. Get Allowed Countries for default scope 0:
   Magento\Directory\Model\ResourceModel\Country::getAllowedCountries('ScopeInterface::SCOPE_STORE, 0)

Expected Result:

1. Returned Allowed Countries for Default config

Actual Result:

1. Will be returned Allowed Countries for default store - Store.

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-engcom-team]

Hi @swnsma. Thank you for your contribution
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[magento-engcom-team]

Hi @miguelbalparda, thank you for the review.
ENGCOM-2281 has been created to process this Pull Request

[magento-engcom-team]

Hi @swnsma. Thank you for your contribution.
We will aim to release these changes as part of 2.2.6.
Please check the release notes for final confirmation.

Please, consider to port this solution to 2.3 release line.
You may use Porting tool to port commits automatically.