code coverage is not generatefor non-app folders

[imanghafoori1]

I have installed xdebug and etc so that I can generate coverage report for my app folder.
But I have a lot of code in a folder beside the app called modules and when I change my phpunit.xml to point to the modules folder, it generates an empty an html report.
php artisan test --coverage-html report

I have no idea why it only generates for the app folder. what is special about the app?

<?xml version="1.0" encoding="UTF-8"?>
<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="./vendor/phpunit/phpunit/phpunit.xsd"
         bootstrap="vendor/autoload.php"
         colors="true"
>
    <testsuites>
        <testsuite name="Unit">
            <directory suffix="">./modules/*/tests/Unit</directory>
        </testsuite>
        <testsuite name="Feature">
            <directory suffix="">./modules/*/tests/Feature</directory>
        </testsuite>
    </testsuites>
    <coverage processUncoveredFiles="true">
        <include>
            <directory suffix=".php">./app</directory>
        </include>
    </coverage>
    <php>
        <env name="APP_ENV" value="testing"/>
        <env name="BCRYPT_ROUNDS" value="4"/>
        <env name="CACHE_DRIVER" value="array"/>
        <env name="DB_CONNECTION" value="testing"/>
        <env name="DB_DATABASE" value=":memory:"/>
        <!-- <env name="MAIL_MAILER" value="array"/> -->
        <env name="QUEUE_CONNECTION" value="sync"/>
        <env name="SESSION_DRIVER" value="array"/>
        <env name="TELESCOPE_ENABLED" value="false"/>
    </php>
</phpunit>

[tylernathanreed]

You need to add another <directory> element within your <coverage> element.