ModuleInstaller::install

public ModuleInstaller::install(array $module_list, $enable_dependencies = TRUE)

$settings['extension_discovery_scan_tests'] = TRUE;

public function install(array $module_list, $enable_dependencies = TRUE) {
  $extension_config = \Drupal::configFactory()->getEditable('core.extension');
  if ($enable_dependencies) {
    // Get all module data so we can find dependencies and sort.
    $module_data = system_rebuild_module_data();
    $module_list = $module_list ? array_combine($module_list, $module_list) : array();
    if ($missing_modules = array_diff_key($module_list, $module_data)) {
      // One or more of the given modules doesn't exist.
      throw new MissingDependencyException(sprintf('Unable to install modules %s due to missing modules %s.', implode(', ', $module_list), implode(', ', $missing_modules)));
    }

    // Only process currently uninstalled modules.
    $installed_modules = $extension_config->get('module') ? : array();
    if (!$module_list = array_diff_key($module_list, $installed_modules)) {
      // Nothing to do. All modules already installed.
      return TRUE;
    }

    // Add dependencies to the list. The new modules will be processed as
    // the while loop continues.
    while (list($module) = each($module_list)) {
      foreach (array_keys($module_data[$module]->requires) as $dependency) {
        if (!isset($module_data[$dependency])) {
          // The dependency does not exist.
          throw new MissingDependencyException("Unable to install modules: module '$module' is missing its dependency module $dependency.");
        }

        // Skip already installed modules.
        if (!isset($module_list[$dependency]) && !isset($installed_modules[$dependency])) {
          $module_list[$dependency] = $dependency;
        }
      }
    }

    // Set the actual module weights.
    $module_list = array_map(function($module) use ($module_data) {
      return $module_data[$module]->sort;
    }, $module_list);

    // Sort the module list by their weights (reverse).
    arsort($module_list);
    $module_list = array_keys($module_list);
  }

  // Required for module installation checks.
  include_once $this->root . '/core/includes/install.inc';

  /** @var \Drupal\Core\Config\ConfigInstaller $config_installer */
  $config_installer = \Drupal::service('config.installer');
  $sync_status = $config_installer->isSyncing();
  if ($sync_status) {
    $source_storage = $config_installer->getSourceStorage();
  }
  $modules_installed = array();
  foreach ($module_list as $module) {
    $enabled = $extension_config->get("module.$module") !== NULL;
    if (!$enabled) {
      // Throw an exception if the module name is too long.
      if (strlen($module) > DRUPAL_EXTENSION_NAME_MAX_LENGTH) {
        throw new ExtensionNameLengthException("Module name '$module' is over the maximum allowed length of " . DRUPAL_EXTENSION_NAME_MAX_LENGTH . ' characters');
      }

      // Check the validity of the default configuration. This will throw
      // exceptions if the configuration is not valid.
      $config_installer->checkConfigurationToInstall('module', $module);

      // Save this data without checking schema. This is a performance
      // improvement for module installation.
      $extension_config
      ->set("module.$module", 0)
        ->set('module', module_config_sort($extension_config->get('module')))
        ->save(TRUE);

      // Prepare the new module list, sorted by weight, including filenames.
      // This list is used for both the ModuleHandler and DrupalKernel. It
      // needs to be kept in sync between both. A DrupalKernel reboot or
      // rebuild will automatically re-instantiate a new ModuleHandler that
      // uses the new module list of the kernel. However, DrupalKernel does
      // not cause any modules to be loaded.
      // Furthermore, the currently active (fixed) module list can be
      // different from the configured list of enabled modules. For all active
      // modules not contained in the configured enabled modules, we assume a
      // weight of 0.
      $current_module_filenames = $this->moduleHandler->getModuleList();
      $current_modules = array_fill_keys(array_keys($current_module_filenames), 0);
      $current_modules = module_config_sort(array_merge($current_modules, $extension_config->get('module')));
      $module_filenames = array();
      foreach ($current_modules as $name => $weight) {
        if (isset($current_module_filenames[$name])) {
          $module_filenames[$name] = $current_module_filenames[$name];
        }
        else {
          $module_path = drupal_get_path('module', $name);
          $pathname = "$module_path/$name.info.yml";
          $filename = file_exists($module_path . "/$name.module") ? "$name.module" : NULL;
          $module_filenames[$name] = new Extension($this->root, 'module', $pathname, $filename);
        }
      }

      // Update the module handler in order to load the module's code.
      // This allows the module to participate in hooks and its existence to
      // be discovered by other modules.
      // The current ModuleHandler instance is obsolete with the kernel
      // rebuild below.
      $this->moduleHandler->setModuleList($module_filenames);
      $this->moduleHandler->load($module);
      module_load_install($module);

      // Clear the static cache of system_rebuild_module_data() to pick up the
      // new module, since it merges the installation status of modules into
      // its statically cached list.
      drupal_static_reset('system_rebuild_module_data');

      // Update the kernel to include it.
      $this->updateKernel($module_filenames);

      // Allow modules to react prior to the installation of a module.
      $this->moduleHandler->invokeAll('module_preinstall', array($module));

      // Now install the module's schema if necessary.
      drupal_install_schema($module);

      // Clear plugin manager caches.
      \Drupal::getContainer()->get('plugin.cache_clearer')->clearCachedDefinitions();

      // Set the schema version to the number of the last update provided by
      // the module, or the minimum core schema version.
      $version = \Drupal::CORE_MINIMUM_SCHEMA_VERSION;
      $versions = drupal_get_schema_versions($module);
      if ($versions) {
        $version = max(max($versions), $version);
      }

      // Notify interested components that this module's entity types and
      // field storage definitions are new. For example, a SQL-based storage
      // handler can use this as an opportunity to create the necessary
      // database tables.
      // @todo Clean this up in https://www.drupal.org/node/2350111.
      $entity_manager = \Drupal::entityManager();
      $update_manager = \Drupal::entityDefinitionUpdateManager();
      foreach ($entity_manager->getDefinitions() as $entity_type) {
        if ($entity_type->getProvider() == $module) {
          $update_manager->installEntityType($entity_type);
        }
        elseif ($entity_type->isSubclassOf(FieldableEntityInterface::CLASS)) {
          // The module being installed may be adding new fields to existing
          // entity types. Field definitions for any entity type defined by
          // the module are handled in the if branch.
          foreach ($entity_manager->getFieldStorageDefinitions($entity_type->id()) as $storage_definition) {
            if ($storage_definition->getProvider() == $module) {
              // If the module being installed is also defining a storage key
              // for the entity type, the entity schema may not exist yet. It
              // will be created later in that case.
              try {
                $update_manager->installFieldStorageDefinition($storage_definition->getName(), $entity_type->id(), $module, $storage_definition);
              }
              catch (EntityStorageException $e) {
                watchdog_exception('system', $e, 'An error occurred while notifying the creation of the @name field storage definition: "!message" in %function (line %line of %file).', ['@name' => $storage_definition->getName()]);
              }
            }
          }
        }
      }

      // Install default configuration of the module.
      $config_installer = \Drupal::service('config.installer');
      if ($sync_status) {
        $config_installer
        ->setSyncing(TRUE)
          ->setSourceStorage($source_storage);
      }
      \Drupal::service('config.installer')->installDefaultConfig('module', $module);

      // If the module has no current updates, but has some that were
      // previously removed, set the version to the value of
      // hook_update_last_removed().
      if ($last_removed = $this->moduleHandler->invoke($module, 'update_last_removed')) {
        $version = max($version, $last_removed);
      }
      drupal_set_installed_schema_version($module, $version);

      // Ensure that all post_update functions are registered already.
      /** @var \Drupal\Core\Update\UpdateRegistry $post_update_registry */
      $post_update_registry = \Drupal::service('update.post_update_registry');
      $post_update_registry->registerInvokedUpdates($post_update_registry->getModuleUpdateFunctions($module));

      // Record the fact that it was installed.
      $modules_installed[] = $module;

      // Drupal's stream wrappers needs to be re-registered in case a
      // module-provided stream wrapper is used later in the same request. In
      // particular, this happens when installing Drupal via Drush, as the
      // 'translations' stream wrapper is provided by Interface Translation
      // module and is later used to import translations.
      \Drupal::service('stream_wrapper_manager')->register();

      // Update the theme registry to include it.
      drupal_theme_rebuild();

      // Modules can alter theme info, so refresh theme data.
      // @todo ThemeHandler cannot be injected into ModuleHandler, since that
      //   causes a circular service dependency.
      // @see https://www.drupal.org/node/2208429
      \Drupal::service('theme_handler')->refreshInfo();

      // In order to make uninstalling transactional if anything uses routes.
      \Drupal::getContainer()->set('router.route_provider.old', \Drupal::service('router.route_provider'));
      \Drupal::getContainer()->set('router.route_provider', \Drupal::service('router.route_provider.lazy_builder'));

      // Allow the module to perform install tasks.
      $this->moduleHandler->invoke($module, 'install');

      // Record the fact that it was installed.
      \Drupal::logger('system')->info('%module module installed.', array('%module' => $module));
    }
  }

  // If any modules were newly installed, invoke hook_modules_installed().
  if (!empty($modules_installed)) {
    \Drupal::getContainer()->set('router.route_provider', \Drupal::service('router.route_provider.old'));
    if (!\Drupal::service('router.route_provider.lazy_builder')->hasRebuilt()) {
      // Rebuild routes after installing module. This is done here on top of
      // \Drupal\Core\Routing\RouteBuilder::destruct to not run into errors on
      // fastCGI which executes ::destruct() after the module installation
      // page was sent already.
      \Drupal::service('router.builder')->rebuild();
    }

    $this->moduleHandler->invokeAll('modules_installed', array($modules_installed));
  }

  return TRUE;
}