Error: Class "AppKernel" doesn't exist or cannot be autoloaded PHP Symfony

Question

I am trying to throw my first unit test with PHPUnit 9.0.0 and Symfony 5.1.8.

I throw the test with the command./vendor/bin/phpunit. However, i obtain the next message:

RuntimeException: Class "AppKernel" doesn't exist or cannot be autoloaded. Check that the KERNEL_CLASS value in phpunit.xml matches the fully-qualified class name of your Kernel or override the "XXXXXXX::createKernel()" method.

I check the phpunit.xml file, but I do not find mistakes.

<?xml version="1.0" encoding="UTF-8"?>

<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="bin/.phpunit/phpunit.xsd"
         backupGlobals="false"
         colors="true"
         bootstrap="tests/bootstrap.php"
>

<php>
    <ini name="error_reporting" value="-1" />
    <server name="APP_ENV" value="test" force="true" />
    <server name="SHELL_VERBOSITY" value="-1" />
    <server name="SYMFONY_PHPUNIT_REMOVE" value="" />
    <server name="SYMFONY_PHPUNIT_VERSION" value="7.5" />
</php>

<testsuites>
    <testsuite name="Project Test Suite">
        <directory>tests</directory>
    </testsuite>
</testsuites>

<filter>
    <whitelist processUncoveredFilesFromWhitelist="true">
        <directory suffix=".php">src</directory>
    </whitelist>
</filter>

<listeners>
    <listener class="Symfony\Bridge\PhpUnit\SymfonyTestsListener" />
</listeners>
</phpunit>

I was looking for some line like "KERNEL" or "createKernel". Where could be the error?

Answer 1

In my case, the solution was check the root namespace (it was not "App") and modify the KERNEL_CLASS field in the.env.test file.