PHPUnit必须要求Composer \ Autoload \ ClassLoader.php吗？

Question

Trying to integrate PHPUnit and my IDE (PhpStorm 2017.2). I'm executing the phpunit.phar file directly (version 5.7.21) as I don't use Composer and don't have it installed.

phpunit.xml

<phpunit bootstrap="phpunit-bootstrap.php">
    <testsuites>
        <testsuite name="Test suite">
            <directory>./</directory>
        </testsuite>
    </testsuites>
</phpunit>

phpunit-bootstrap.php

spl_autoload_register('my_autoload');

/**
 * @param string $className Fully qualified name to autoload
 */
function my_autoload($className){
    require $_SERVER['DOCUMENT_ROOT'] . "\\$className.php";
}

This autoloader works fine when I execute my project files. However when I try to run any PHPUnit test, I see this error:

Fatal error: require(): Failed opening required '\Composer\Autoload\ClassLoader.php'

If I remove the autoload, then my project classes can no longer be found (same error, different class name).

Does PHPUnit depend on Composer being installed globally and available on the system path?

Update 1

Following kuba's suggestion in comments, I changed the autoload to:

require __DIR__ . "\\$className.php";

New error:

Fatal error: require(): Failed opening required 'C:\project-root\Composer\Autoload\ClassLoader.php'

Answer 1

I needed to adjust my autoloader to do nothing when PHP tried to load Composer\Autoload\ClassLoader.php. So I changed my Autoloader from:

function my_autoload($className){
    require __DIR__ . "\\$className.php";
}

to

function my_autoload($className){
    $path = __DIR__ . "\\$className.php";
    if (file_exists($path)) require $path;
}