CircleCI로 PHPUnit 코드 커버리지를 출력

test:
  override:
    - ./vendor/bin/phpunit --coverage-html=$CIRCLE_ARTIFACTS

<phpunit backupGlobals="false"
         backupStaticAttributes="false"
         bootstrap="bootstrap/autoload.php"
         colors="true"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         processIsolation="false"
         stopOnFailure="false">
    ---(中略)---
    <filter>
        <whitelist processUncoveredFilesFromWhitelist="true">
            <directory suffix=".php">./app</directory>
            <directory suffix=".php">./domain</directory>
            <directory suffix=".php">./infra</directory>
        </whitelist>
    </filter>
    ---(中略)---
</phpunit>