ModuleLegacyTest.php

<?php

namespace Drupal\KernelTests\Core\Extension;

use Drupal\KernelTests\KernelTestBase;

/**
 * Tests deprecations from module.inc file.
 *
 * @group legacy
 */
class ModuleLegacyTest extends KernelTestBase {
    
    /**
     * Test deprecation of module_load_include() function.
     */
    public function testModuleLoadInclude() {
        $this->assertFalse($this->container
            ->get('module_handler')
            ->moduleExists('module_test'), 'Ensure module is uninstalled so we test the ability to include uninstalled code.');
        $this->expectDeprecation('module_load_include() is deprecated in drupal:9.4.0 and is removed from drupal:11.0.0. Instead, you should use \\Drupal::moduleHandler()->loadInclude(). Note that including code from uninstalled extensions is no longer supported. See https://www.drupal.org/node/2948698');
        $filename = module_load_include('inc', 'module_test', 'module_test.file');
        $this->assertStringEndsWith("module_test.file.inc", $filename);
    }

}