问在PHPUnit中使用命名空间时“找不到类”

EN

./phpunit.xml

./lib/Application/
  -> Dir1/File1.php (namespace = Application\Dir1)
  -> Dir1/File2.php
  -> Dir2/File1.php (namespace = Application\Dir2)

./tests/Application/Tests
  -> Test1.php (namespace = Application\Tests)
  -> Test2.php 

<?xml version="1.0" encoding="UTF-8"?>
<phpunit verbose="false">
  <testsuites>
      <testsuite name="Application">
          <directory>./tests/Application/Tests</directory>
      </testsuite>
  </testsuites>
  <logging>
       <log type="coverage-text" target="php://stdout" showUncoveredFiles="false"/>
       <log type="json" target="/tmp/phpunit-logfile.json"/>
  </logging>
  <filter>
        <whitelist>
            <directory suffix=".php">./lib</directory>
        </whitelist>
  </filter>
</phpunit>

namespace Application\Tests;

use Application\Dir1\File1;

class MyTest extends File1 {}