I am trying to run the Magento web api tests by running the following command:

vendor/bin/phpunit --config ./dev/tests/api-functional/phpunit_rest.xml

But it gives this error:

PHP Fatal error:  Uncaught PHPUnit\Framework\Exception: Could not read "".


  thrown in /var/www/osp.example.com/magento-headless/Magento2/vendor/phpunit/phpunit/src/Util/Xml.php on line 135

After a lot of debugging, I see that WebpApiTest.php runs the function getConfigurationFile which gives back an empty string. This is the code of that function:

     * Returns config file name from command line params.
     * @return string
    private static function getConfigurationFile(): string
        $params = getopt('c:', ['configuration:']);

        $longConfig = $params['configuration'] ?? '';
        $shortConfig = $params['c'] ?? '';

        return $shortConfig ? $shortConfig : $longConfig;

I don't really get what its doing and which information it is supposed to return. Can anyone check what kinda information it is supposed to return? Maybe then I can fix it and run the webapi tests of Magento 2.

  • Did you fix this issue? Commented Aug 5, 2021 at 17:09

2 Answers 2


Does the file ./dev/tests/api-functional/phpunit_rest.xml exist?

Magento includes ".dist" versions of configuration files for certain tools. The first step to using them is to make a copy without the ".dist" extension (thus preserving the original as a backup/reference).


It seems like PHPUnit tries to find a file named after the name-attribute of the testsuite-tag

  1. if it either cannot find any tests (wrong naming or wrong directory)
  2. here is a fatal error occuring in a test-script; which occures so early that PHPUnit cannot identify the content of that file as a test - as no class could be loaded up until that point.

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