ModuleImplementsAlterTest.php

<?php

namespace Drupal\KernelTests\Core\Extension;

use Drupal\KernelTests\KernelTestBase;

/**
 * Tests hook_module_implements_alter().
 *
 * @group Module
 */
class ModuleImplementsAlterTest extends KernelTestBase {
    
    /**
     * {@inheritdoc}
     */
    public static $modules = [
        'system',
    ];
    
    /**
     * Tests hook_module_implements_alter() adding an implementation.
     *
     * @see \Drupal\Core\Extension\ModuleHandler::buildImplementationInfo()
     * @see module_test_module_implements_alter()
     */
    public function testModuleImplementsAlter() {
        // Get an instance of the module handler, to observe how it is going to be
        // replaced.
        $module_handler = \Drupal::moduleHandler();
        $this->assertTrue($module_handler === \Drupal::moduleHandler(), 'Module handler instance is still the same.');
        // Install the module_test module.
        \Drupal::service('module_installer')->install([
            'module_test',
        ]);
        // Assert that the \Drupal::moduleHandler() instance has been replaced.
        $this->assertFalse($module_handler === \Drupal::moduleHandler(), 'The \\Drupal::moduleHandler() instance has been replaced during \\Drupal::moduleHandler()->install().');
        // Assert that module_test.module is now included.
        $this->assertTrue(function_exists('module_test_modules_installed'), 'The file module_test.module was successfully included.');
        $this->assertArrayHasKey('module_test', \Drupal::moduleHandler()->getModuleList());
        $this->assertContains('module_test', \Drupal::moduleHandler()->getImplementations('modules_installed'), 'module_test implements hook_modules_installed().');
        $this->assertContains('module_test', \Drupal::moduleHandler()->getImplementations('module_implements_alter'), 'module_test implements hook_module_implements_alter().');
        // Assert that module_test.implementations.inc is not included yet.
        $this->assertFalse(function_exists('module_test_altered_test_hook'), 'The file module_test.implementations.inc is not included yet.');
        // Trigger hook discovery for hook_altered_test_hook().
        // Assert that module_test_module_implements_alter(*, 'altered_test_hook')
        // has added an implementation.
        $this->assertContains('module_test', \Drupal::moduleHandler()->getImplementations('altered_test_hook'), 'module_test implements hook_altered_test_hook().');
        // Assert that module_test.implementations.inc was included as part of the process.
        $this->assertTrue(function_exists('module_test_altered_test_hook'), 'The file module_test.implementations.inc was included.');
    }
    
    /**
     * Tests what happens if hook_module_implements_alter() adds a non-existing
     * function to the implementations.
     *
     * @see \Drupal\Core\Extension\ModuleHandler::buildImplementationInfo()
     * @see module_test_module_implements_alter()
     */
    public function testModuleImplementsAlterNonExistingImplementation() {
        // Install the module_test module.
        \Drupal::service('module_installer')->install([
            'module_test',
        ]);
        // Trigger hook discovery.
        $this->expectException(\RuntimeException::class);
        $this->expectExceptionMessage('An invalid implementation module_test_unimplemented_test_hook was added by hook_module_implements_alter()');
        \Drupal::moduleHandler()->getImplementations('unimplemented_test_hook');
    }

}