Merge pull request #28521 from woocommerce/fix/26475

Create additional download permissions on product save if needed

includes/class-woocommerce.php

@@ -8,6 +8,7 @@
 
 defined( 'ABSPATH' ) || exit;
 
+use Automattic\WooCommerce\Internal\DownloadPermissionsAdjuster;
 use Automattic\WooCommerce\Proxies\LegacyProxy;
 
 /**
@@ -202,6 +203,9 @@ final class WooCommerce {
 		add_action( 'switch_blog', array( $this, 'wpdb_table_fix' ), 0 );
 		add_action( 'activated_plugin', array( $this, 'activated_plugin' ) );
 		add_action( 'deactivated_plugin', array( $this, 'deactivated_plugin' ) );
+
+		// These classes set up hooks on instantiation.
+		wc_get_container()->get( DownloadPermissionsAdjuster::class );
 	}
 
 	/**
@@ -901,7 +905,7 @@ final class WooCommerce {
 			'https://wordpress.org/plugins/woocommerce/',
 			'https://github.com/woocommerce/woocommerce/releases'
 		);
-		printf( '<div class="error"><p>%s %s</p></div>', $message_one, $message_two ); /* WPCS: xss ok. */
+		printf( '<div class="error"><p>%s %s</p></div>', $message_one, $message_two ); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 	}
 
 	/**

includes/data-stores/class-wc-customer-download-data-store.php

@@ -16,6 +16,38 @@ if ( ! defined( 'ABSPATH' ) ) {
  */
 class WC_Customer_Download_Data_Store implements WC_Customer_Download_Data_Store_Interface {
 
+	/**
+	 * Names of the database fields for the download permissions table.
+	 */
+	const DOWNLOAD_PERMISSION_DB_FIELDS = array(
+		'download_id',
+		'product_id',
+		'user_id',
+		'user_email',
+		'order_id',
+		'order_key',
+		'downloads_remaining',
+		'access_granted',
+		'download_count',
+		'access_expires',
+	);
+
+	/**
+	 * Create download permission for a user, from an array of data.
+	 *
+	 * @param array $data Data to create the permission for.
+	 * @returns int The database id of the created permission, or false if the permission creation failed.
+	 */
+	public function create_from_data( $data ) {
+		$data = array_intersect_key( $data, array_flip( self::DOWNLOAD_PERMISSION_DB_FIELDS ) );
+
+		$id = $this->insert_new_download_permission( $data );
+
+		do_action( 'woocommerce_grant_product_download_access', $data );
+
+		return $id;
+	}
+
 	/**
 	 * Create download permission for a user.
 	 *
@@ -29,18 +61,41 @@ class WC_Customer_Download_Data_Store implements WC_Customer_Download_Data_Store
 			$download->set_access_granted( time() );
 		}
 
-		$data = array(
-			'download_id'         => $download->get_download_id( 'edit' ),
-			'product_id'          => $download->get_product_id( 'edit' ),
-			'user_id'             => $download->get_user_id( 'edit' ),
-			'user_email'          => $download->get_user_email( 'edit' ),
-			'order_id'            => $download->get_order_id( 'edit' ),
-			'order_key'           => $download->get_order_key( 'edit' ),
-			'downloads_remaining' => $download->get_downloads_remaining( 'edit' ),
-			'access_granted'      => date( 'Y-m-d', $download->get_access_granted( 'edit' )->getTimestamp() ),
-			'download_count'      => $download->get_download_count( 'edit' ),
-			'access_expires'      => ! is_null( $download->get_access_expires( 'edit' ) ) ? date( 'Y-m-d', $download->get_access_expires( 'edit' )->getTimestamp() ) : null,
-		);
+		$data = array();
+		foreach ( self::DOWNLOAD_PERMISSION_DB_FIELDS as $db_field_name ) {
+			$value                  = call_user_func( array( $download, 'get_' . $db_field_name ), 'edit' );
+			$data[ $db_field_name ] = $value;
+		}
+
+		$inserted_id = $this->insert_new_download_permission( $data );
+		if ( $inserted_id ) {
+			$download->set_id( $inserted_id );
+			$download->apply_changes();
+		}
+
+		do_action( 'woocommerce_grant_product_download_access', $data );
+	}
+
+	/**
+	 * Create download permission for a user, from an array of data.
+	 * Assumes that all the keys in the passed data are valid.
+	 *
+	 * @param array $data Data to create the permission for.
+	 * @return int The database id of the created permission, or false if the permission creation failed.
+	 */
+	private function insert_new_download_permission( $data ) {
+		global $wpdb;
+
+		// Always set a access granted date.
+		if ( ! isset( $data['access_granted'] ) ) {
+			$data['access_granted'] = time();
+		}
+
+		$data['access_granted'] = $this->adjust_date_for_db( $data['access_granted'] );
+
+		if ( isset( $data['access_expires'] ) ) {
+			$data['access_expires'] = $this->adjust_date_for_db( $data['access_expires'] );
+		}
 
 		$format = array(
 			'%s',
@@ -61,12 +116,29 @@ class WC_Customer_Download_Data_Store implements WC_Customer_Download_Data_Store
 			apply_filters( 'woocommerce_downloadable_file_permission_format', $format, $data )
 		);
 
-		if ( $result ) {
-			$download->set_id( $wpdb->insert_id );
-			$download->apply_changes();
+		return $result ? $wpdb->insert_id : false;
+	}
+
+	/**
+	 * Adjust a date value to be inserted in the database.
+	 *
+	 * @param mixed $date The date value. Can be a WC_DateTime, a timestamp, or anything else that "date" recognizes.
+	 * @return string The date converted to 'Y-m-d' format.
+	 * @throws Exception The passed value can't be converted to a date.
+	 */
+	private function adjust_date_for_db( $date ) {
+		if ( 'WC_DateTime' === get_class( $date ) ) {
+			$date = $date->getTimestamp();
 		}
 
-		do_action( 'woocommerce_grant_product_download_access', $data );
+		$adjusted_date = date( 'Y-m-d', $date ); // phpcs:ignore WordPress.DateTime.RestrictedFunctions.date_date
+
+		if ( $adjusted_date ) {
+			return $adjusted_date;
+		}
+
+		$msg = sprintf( __( "I don't know how to get a date from a %s", 'woocommerce' ), is_object( $date ) ? get_class( $date ) : gettype( $date ) );
+		throw new Exception( $msg );
 	}
 
 	/**
@@ -128,8 +200,10 @@ class WC_Customer_Download_Data_Store implements WC_Customer_Download_Data_Store
 			'order_id'            => $download->get_order_id( 'edit' ),
 			'order_key'           => $download->get_order_key( 'edit' ),
 			'downloads_remaining' => $download->get_downloads_remaining( 'edit' ),
+			// phpcs:ignore WordPress.DateTime.RestrictedFunctions.date_date
 			'access_granted'      => date( 'Y-m-d', $download->get_access_granted( 'edit' )->getTimestamp() ),
 			'download_count'      => $download->get_download_count( 'edit' ),
+			// phpcs:ignore WordPress.DateTime.RestrictedFunctions.date_date
 			'access_expires'      => ! is_null( $download->get_access_expires( 'edit' ) ) ? date( 'Y-m-d', $download->get_access_expires( 'edit' )->getTimestamp() ) : null,
 		);
 
@@ -412,7 +486,7 @@ class WC_Customer_Download_Data_Store implements WC_Customer_Download_Data_Store
 					)
 				ORDER BY permissions.order_id, permissions.product_id, permissions.permission_id;",
 				$customer_id,
-				date( 'Y-m-d', current_time( 'timestamp' ) )
+				date( 'Y-m-d', current_time( 'timestamp' ) )  // phpcs:ignore WordPress.DateTime.RestrictedFunctions.date_date
 			)
 		);
 	}

includes/data-stores/class-wc-product-data-store-cpt.php

@@ -6,6 +6,7 @@
  */
 
 use Automattic\Jetpack\Constants;
+use Automattic\WooCommerce\Internal\DownloadPermissionsAdjuster;
 use Automattic\WooCommerce\Utilities\NumberUtil;
 
 if ( ! defined( 'ABSPATH' ) ) {
@@ -265,6 +266,10 @@ class WC_Product_Data_Store_CPT extends WC_Data_Store_WP implements WC_Object_Da
 		$this->handle_updated_props( $product );
 		$this->clear_caches( $product );
 
+		wc_get_container()
+			->get( DownloadPermissionsAdjuster::class )
+			->maybe_schedule_adjust_download_permissions( $product );
+
 		$product->apply_changes();
 
 		do_action( 'woocommerce_update_product', $product->get_id(), $product );

src/Container.php

@@ -5,8 +5,9 @@
 
 namespace Automattic\WooCommerce;
 
-use Automattic\WooCommerce\Internal\DependencyManagement\ServiceProviders\ProxiesServiceProvider;
 use Automattic\WooCommerce\Internal\DependencyManagement\ExtendedContainer;
+use Automattic\WooCommerce\Internal\DependencyManagement\ServiceProviders\DownloadPermissionsAdjusterServiceProvider;
+use Automattic\WooCommerce\Internal\DependencyManagement\ServiceProviders\ProxiesServiceProvider;
 
 /**
  * PSR11 compliant dependency injection container for WooCommerce.
@@ -33,6 +34,7 @@ final class Container implements \Psr\Container\ContainerInterface {
 	 */
 	private $service_providers = array(
 		ProxiesServiceProvider::class,
+		DownloadPermissionsAdjusterServiceProvider::class,
 	);
 
 	/**

src/Internal/DependencyManagement/ServiceProviders/DownloadPermissionsAdjusterServiceProvider.php

@@ -0,0 +1,31 @@
+<?php
+/**
+ * DownloadPermissionsAdjusterServiceProvider class file.
+ */
+
+namespace Automattic\WooCommerce\Internal\DependencyManagement\ServiceProviders;
+
+use Automattic\WooCommerce\Internal\DependencyManagement\AbstractServiceProvider;
+use Automattic\WooCommerce\Internal\DownloadPermissionsAdjuster;
+
+/**
+ * Service provider for the DownloadPermissionsAdjuster class.
+ */
+class DownloadPermissionsAdjusterServiceProvider extends AbstractServiceProvider {
+
+	/**
+	 * The classes/interfaces that are serviced by this service provider.
+	 *
+	 * @var array
+	 */
+	protected $provides = array(
+		DownloadPermissionsAdjuster::class,
+	);
+
+	/**
+	 * Register the classes.
+	 */
+	public function register() {
+		$this->share( DownloadPermissionsAdjuster::class );
+	}
+}

src/Internal/DependencyManagement/ServiceProviders/ProxiesServiceProvider.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Proxies class file.
+ * ProxiesServiceProvider class file.
  */
 
 namespace Automattic\WooCommerce\Internal\DependencyManagement\ServiceProviders;

src/Internal/DownloadPermissionsAdjuster.php

@@ -0,0 +1,160 @@
+<?php
+/**
+ * DownloadPermissionsAdjuster class file.
+ */
+
+namespace Automattic\WooCommerce\Internal;
+
+use Automattic\WooCommerce\Proxies\LegacyProxy;
+
+defined( 'ABSPATH' ) || exit;
+
+/**
+ * Class to adjust download permissions on product save.
+ */
+class DownloadPermissionsAdjuster {
+
+	/**
+	 * The downloads data store to use.
+	 *
+	 * @var WC_Data_Store
+	 */
+	private $downloads_data_store;
+
+	/**
+	 * Class initialization, to be executed when the class is resolved by the container.
+	 *
+	 * @internal
+	 */
+	final public function init() {
+		$this->downloads_data_store = wc_get_container()->get( LegacyProxy::class )->get_instance_of( \WC_Data_Store::class, 'customer-download' );
+		add_action( 'adjust_download_permissions', array( $this, 'adjust_download_permissions' ), 10, 1 );
+	}
+
+	/**
+	 * Schedule a download permissions adjustment for a product if necessary.
+	 * This should be executed whenever a product is saved.
+	 *
+	 * @param \WC_Product $product The product to schedule a download permission adjustments for.
+	 */
+	public function maybe_schedule_adjust_download_permissions( \WC_Product $product ) {
+		$children_ids = $product->get_children();
+		if ( ! $children_ids ) {
+			return;
+		}
+
+		$scheduled_action_args = array( $product->get_id() );
+
+		$already_scheduled_actions =
+			WC()->call_function(
+				'as_get_scheduled_actions',
+				array(
+					'hook'   => 'adjust_download_permissions',
+					'args'   => $scheduled_action_args,
+					'status' => \ActionScheduler_Store::STATUS_PENDING,
+				),
+				'ids'
+			);
+
+		if ( empty( $already_scheduled_actions ) ) {
+			WC()->call_function(
+				'as_schedule_single_action',
+				WC()->call_function( 'time' ) + 1,
+				'adjust_download_permissions',
+				$scheduled_action_args
+			);
+		}
+	}
+
+	/**
+	 * Create additional download permissions for variations if necessary.
+	 *
+	 * When a simple downloadable product is converted to a variable product,
+	 * existing download permissions are still present in the database but they don't apply anymore.
+	 * This method creates additional download permissions for the variations based on
+	 * the old existing ones for the main product.
+	 *
+	 * The procedure is as follows. For each existing download permission for the parent product,
+	 * check if there's any variation offering the same file for download (the file URL, not name, is checked).
+	 * If that is found, check if an equivalent permission exists (equivalent means for the same file and with
+	 * the same order id and customer id). If no equivalent permission exists, create it.
+	 *
+	 * @param int $product_id The id of the product to check permissions for.
+	 */
+	public function adjust_download_permissions( int $product_id ) {
+		$product = wc_get_product( $product_id );
+
+		$children_ids = $product->get_children();
+		if ( ! $children_ids ) {
+			return;
+		}
+
+		$parent_downloads = $this->get_download_files_and_permissions( $product );
+		if ( ! $parent_downloads ) {
+			return;
+		}
+
+		$children_with_downloads = array();
+		foreach ( $children_ids as $child_id ) {
+			$child                                = wc_get_product( $child_id );
+			$children_with_downloads[ $child_id ] = $this->get_download_files_and_permissions( $child );
+		}
+
+		foreach ( $parent_downloads['permission_data_by_file_order_user'] as $parent_file_order_and_user => $parent_download_data ) {
+			foreach ( $children_with_downloads as $child_id => $child_download_data ) {
+				$file_url = $parent_download_data['file'];
+
+				$must_create_permission =
+					// The variation offers the same file as the parent for download...
+					in_array( $file_url, array_keys( $child_download_data['download_ids_by_file_url'] ), true ) &&
+					// ...but no equivalent download permission (same file URL, order id and user id) exists.
+					! array_key_exists( $parent_file_order_and_user, $child_download_data['permission_data_by_file_order_user'] );
+
+				if ( $must_create_permission ) {
+					// The new child download permission is a copy of the parent's,
+					// but with the product and download ids changed to match those of the variation.
+					$new_download_data                = $parent_download_data['data'];
+					$new_download_data['product_id']  = $child_id;
+					$new_download_data['download_id'] = $child_download_data['download_ids_by_file_url'][ $file_url ];
+					$this->downloads_data_store->create_from_data( $new_download_data );
+				}
+			}
+		}
+	}
+
+	/**
+	 * Get the existing downloadable files and download permissions for a given product.
+	 * The returned value is an array with two keys:
+	 *
+	 * - download_ids_by_file_url: an associative array of file url => download_id.
+	 * - permission_data_by_file_order_user: an associative array where key is "file_url:customer_id:order_id" and value is the full permission data set.
+	 *
+	 * @param \WC_Product $product The product to get the downloadable files and permissions for.
+	 * @return array[] Information about the downloadable files and permissions for the product.
+	 */
+	private function get_download_files_and_permissions( \WC_Product $product ) {
+		$result    = array(
+			'permission_data_by_file_order_user' => array(),
+			'download_ids_by_file_url'           => array(),
+		);
+		$downloads = $product->get_downloads();
+		foreach ( $downloads as $download ) {
+			$result['download_ids_by_file_url'][ $download->get_file() ] = $download->get_id();
+		}
+
+		$permissions = $this->downloads_data_store->get_downloads( array( 'product_id' => $product->get_id() ) );
+		foreach ( $permissions as $permission ) {
+			$permission_data = (array) $permission->data;
+			if ( array_key_exists( $permission_data['download_id'], $downloads ) ) {
+				$file = $downloads[ $permission_data['download_id'] ]->get_file();
+				$data = array(
+					'file' => $file,
+					'data' => (array) $permission->data,
+				);
+				$result['permission_data_by_file_order_user'][ "${file}:${permission_data['user_id']}:${permission_data['order_id']}" ] = $data;
+			}
+		}
+
+		return $result;
+	}
+}

src/Proxies/LegacyProxy.php

@@ -52,6 +52,11 @@ class LegacyProxy {
 			return $class_name::instance( ...$args );
 		}
 
+		// If the class has a "load" method, use it.
+		if ( method_exists( $class_name, 'load' ) ) {
+			return $class_name::load( ...$args );
+		}
+
 		// Fallback to simply creating a new instance of the class.
 		return new $class_name( ...$args );
 	}

tests/php/src/Internal/DependencyManagement/ExampleClasses/ClassWithLoadMethod.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * ClassWithSingleton class file.
+ */
+
+// This class is in the root namespace on purpose, since it simulates being a legacy class in the 'includes' directory.
+
+/**
+ * An example of a class that holds a singleton instance.
+ */
+class ClassWithLoadMethod {
+
+	/**
+	 * @var ClassWithLoadMethod The last instance of the class that has been loaded.
+	 */
+	public static $loaded;
+
+	/**
+	 * @var array The arguments supplied to 'load'.
+	 */
+	public static $loaded_args;
+
+	/**
+	 * Load an instance of the class.
+	 *
+	 * @param mixed ...$args Any arguments required by the method.
+	 *
+	 * @return ClassWithLoadMethod The singleton instance of the class.
+	 */
+	public static function load( ...$args ) {
+		self::$loaded      = new ClassWithLoadMethod();
+		self::$loaded_args = $args;
+		return self::$loaded;
+	}
+}

tests/php/src/Internal/DownloadPermissionsAdjusterTest.php

@@ -0,0 +1,358 @@
+<?php
+/**
+ * DownloadPermissionsAdjusterTest class file.
+ */
+
+namespace Automattic\WooCommerce\Tests\Internal;
+
+use Automattic\WooCommerce\Internal\DownloadPermissionsAdjuster;
+use Automattic\WooCommerce\RestApi\UnitTests\Helpers\ProductHelper;
+
+/**
+ * Tests for DownloadPermissionsAdjuster.
+ */
+class DownloadPermissionsAdjusterTest extends \WC_Unit_Test_Case {
+
+	/**
+	 * The system under test.
+	 *
+	 * @var DownloadPermissionsAdjuster
+	 */
+	private $sut;
+
+	/**
+	 * Runs before each test.
+	 */
+	public function setUp() {
+		$this->sut = new DownloadPermissionsAdjuster();
+		$this->sut->init();
+
+		// This is needed for "product->set_downloads" to work without actual files.
+		add_filter(
+			'woocommerce_downloadable_file_allowed_mime_types',
+			function() {
+				return array( 'foo' => 'nonsense/foo' );
+			}
+		);
+		add_filter(
+			'woocommerce_downloadable_file_exists',
+			function( $exists, $filename ) {
+				return true;
+			},
+			10,
+			2
+		);
+	}
+
+	/**
+	 * @testdox DownloadPermissionsAdjuster class hooks on 'adjust_download_permissions' on initialization.
+	 */
+	public function test_class_hooks_on_adjust_download_permissions() {
+		remove_all_actions( 'adjust_download_permissions' );
+		$this->assertFalse( has_action( 'adjust_download_permissions' ) );
+		$this->setUp();
+		$this->assertTrue( has_action( 'adjust_download_permissions' ) );
+	}
+
+	/**
+	 * @testdox 'maybe_schedule_adjust_download_permissions' does nothing if the product has no children.
+	 */
+	public function test_no_adjustment_is_scheduled_if_product_has_no_children() {
+		$as_get_scheduled_actions_invoked  = false;
+		$as_schedule_single_action_invoked = false;
+
+		$this->register_legacy_proxy_function_mocks(
+			array(
+				'as_get_scheduled_actions'  => function( $args, $return_format ) use ( &$as_get_scheduled_actions_invoked ) {
+					$as_get_scheduled_actions_invoked = true;
+				},
+				'as_schedule_single_action' => function( $timestamp, $hook, $args ) use ( &$as_schedule_single_action_invoked ) {
+					$as_schedule_single_action_invoked = true;
+				},
+			)
+		);
+
+		$product = ProductHelper::create_simple_product();
+		$this->sut->maybe_schedule_adjust_download_permissions( $product );
+
+		$this->assertFalse( $as_get_scheduled_actions_invoked );
+		$this->assertFalse( $as_schedule_single_action_invoked );
+	}
+
+	/**
+	 * @testdox 'maybe_schedule_adjust_download_permissions' does nothing if the an adjustment is already pending.
+	 */
+	public function test_no_adjustment_is_scheduled_if_already_scheduled() {
+		$as_get_scheduled_actions_args     = null;
+		$as_schedule_single_action_invoked = false;
+
+		$this->register_legacy_proxy_function_mocks(
+			array(
+				'as_get_scheduled_actions'  => function( $args, $return_format ) use ( &$as_get_scheduled_actions_args ) {
+					$as_get_scheduled_actions_args = $args;
+					return array( 1 );
+				},
+				'as_schedule_single_action' => function( $timestamp, $hook, $args ) use ( &$as_schedule_single_action_invoked ) {
+					$as_schedule_single_action_invoked = true;
+				},
+			)
+		);
+
+		$product = ProductHelper::create_variation_product();
+		$this->sut->maybe_schedule_adjust_download_permissions( $product );
+
+		$expected_get_scheduled_actions_args = array(
+			'hook'   => 'adjust_download_permissions',
+			'args'   => array( $product->get_id() ),
+			'status' => \ActionScheduler_Store::STATUS_PENDING,
+		);
+		$this->assertEquals( $expected_get_scheduled_actions_args, $as_get_scheduled_actions_args );
+		$this->assertFalse( $as_schedule_single_action_invoked );
+	}
+
+	/**
+	 * @testdox 'maybe_schedule_adjust_download_permissions' schedules an adjustment if not scheduled already.
+	 */
+	public function test_no_adjustment_is_scheduled_if_not_yet_scheduled() {
+		$as_get_scheduled_actions_args  = null;
+		$as_schedule_single_action_args = null;
+
+		$this->register_legacy_proxy_function_mocks(
+			array(
+				'as_get_scheduled_actions'  => function( $params, $return_format ) use ( &$as_get_scheduled_actions_args ) {
+					$as_get_scheduled_actions_args = $params;
+					return array();
+				},
+				'as_schedule_single_action' => function( $timestamp, $hook, $args ) use ( &$as_schedule_single_action_args ) {
+					$as_schedule_single_action_args = array( $timestamp, $hook, $args );
+				},
+				'time'                      => function() {
+					return 0; },
+			)
+		);
+
+		$product = ProductHelper::create_variation_product();
+		$this->sut->maybe_schedule_adjust_download_permissions( $product );
+
+		$expected_get_scheduled_actions_args = array(
+			'hook'   => 'adjust_download_permissions',
+			'args'   => array( $product->get_id() ),
+			'status' => \ActionScheduler_Store::STATUS_PENDING,
+		);
+		$this->assertEquals( $expected_get_scheduled_actions_args, $as_get_scheduled_actions_args );
+
+		$expected_as_schedule_single_action_args = array(
+			1,
+			'adjust_download_permissions',
+			array( $product->get_id() ),
+		);
+		$this->assertEquals( $expected_as_schedule_single_action_args, $as_schedule_single_action_args );
+	}
+
+	/**
+	 * @testdox 'adjust_download_permissions' creates child download permissions when they are missing (see method comment for details).
+	 */
+	public function test_adjust_download_permissions_creates_additional_permissions_if_not_exist() {
+		$download = array(
+			'name' => 'the_file',
+			'file' => 'the_file.foo',
+		);
+
+		$product = ProductHelper::create_variation_product();
+		$product->set_downloads( array( $download ) );
+		$product->save();
+		$parent_download_id = current( $product->get_downloads() )->get_id();
+
+		$child = wc_get_product( current( $product->get_children() ) );
+		$child->set_downloads( array( $download ) );
+		$child->save();
+		$child_download_id = current( $child->get_downloads() )->get_id();
+
+		$data_for_data_store =
+			array(
+				$product->get_id() =>
+				array(
+					(object) array(
+						'data' => array(
+							'download_id'         => $parent_download_id,
+							'user_id'             => 1234,
+							'order_id'            => 5678,
+							'downloads_remaining' => 34,
+							'access_granted'      => '2000-01-01',
+							'access_expires'      => '2034-02-27',
+						),
+					),
+				),
+			);
+
+		$data_store = $this->create_mock_data_store( $data_for_data_store );
+
+		$this->setUp();
+		$this->sut->adjust_download_permissions( $product->get_id() );
+
+		$expected_created_data = array(
+			'download_id'         => $child_download_id,
+			'user_id'             => 1234,
+			'order_id'            => 5678,
+			'product_id'          => $child->get_id(),
+			'downloads_remaining' => 34,
+			'access_granted'      => '2000-01-01',
+			'access_expires'      => '2034-02-27',
+		);
+
+		$this->assertEquals( $expected_created_data, $data_store->created_data );
+	}
+
+	/**
+	 * @testdox 'adjust_download_permissions' doesn't create child download permissions that already exist.
+	 */
+	public function test_adjust_download_permissions_dont_create_additional_permissions_if_already_exists() {
+		$download = array(
+			'name' => 'the_file',
+			'file' => 'the_file.foo',
+		);
+
+		$product = ProductHelper::create_variation_product();
+		$product->set_downloads( array( $download ) );
+		$product->save();
+		$parent_download_id = current( $product->get_downloads() )->get_id();
+
+		$child = wc_get_product( current( $product->get_children() ) );
+		$child->set_downloads( array( $download ) );
+		$child->save();
+		$child_download_id = current( $child->get_downloads() )->get_id();
+
+		$data_for_data_store =
+			array(
+				$product->get_id() =>
+					array(
+						(object) array(
+							'data' => array(
+								'download_id' => $parent_download_id,
+								'user_id'     => 1234,
+								'order_id'    => 5678,
+							),
+						),
+					),
+				$child->get_id()   =>
+					array(
+						(object) array(
+							'data' => array(
+								'download_id' => $child_download_id,
+								'user_id'     => 1234,
+								'order_id'    => 5678,
+							),
+						),
+					),
+			);
+
+		$data_store = $this->create_mock_data_store( $data_for_data_store );
+
+		$this->setUp();
+		$this->sut->adjust_download_permissions( $product->get_id() );
+
+		$this->assertEmpty( $data_store->created_data );
+	}
+
+	/**
+	 * @testdox 'adjust_download_permissions' creates child download permissions when one exists but for a different order or customer id.
+	 *
+	 * @testWith [9999, 5678]
+	 *           [1234, 9999]
+	 * @param int $user_id User id the child download permission exists for.
+	 * @param int $order_id Order id the child download permission exists for.
+	 */
+	public function test_adjust_download_permissions_creates_additional_permissions_if_exists_but_not_matching( $user_id, $order_id ) {
+		$download = array(
+			'name' => 'the_file',
+			'file' => 'the_file.foo',
+		);
+
+		$product = ProductHelper::create_variation_product();
+		$product->set_downloads( array( $download ) );
+		$product->save();
+		$parent_download_id = current( $product->get_downloads() )->get_id();
+
+		$child = wc_get_product( current( $product->get_children() ) );
+		$child->set_downloads( array( $download ) );
+		$child->save();
+		$child_download_id = current( $child->get_downloads() )->get_id();
+
+		$data_for_data_store =
+			array(
+				$product->get_id() =>
+					array(
+						(object) array(
+							'data' => array(
+								'download_id' => $parent_download_id,
+								'user_id'     => 1234,
+								'order_id'    => 5678,
+							),
+						),
+					),
+				$child->get_id()   =>
+					array(
+						(object) array(
+							'data' => array(
+								'download_id' => $child_download_id,
+								'user_id'     => $user_id,
+								'order_id'    => $order_id,
+							),
+						),
+					),
+			);
+
+		$data_store = $this->create_mock_data_store( $data_for_data_store );
+
+		$this->setUp();
+		$this->sut->adjust_download_permissions( $product->get_id() );
+
+		$expected = array(
+			'download_id' => $child_download_id,
+			'user_id'     => 1234,
+			'order_id'    => 5678,
+			'product_id'  => $child->get_id(),
+		);
+
+		$this->assertEquals( $expected, $data_store->created_data );
+	}
+
+	/**
+	 * Create and register a mock customer downloads data store.
+	 *
+	 * @param array $data An array where keys are product ids, and values are what 'get_downloads' will return for that input.
+	 * @return object An object that mocks the customer downloads data store.
+	 */
+	private function create_mock_data_store( $data ) {
+		// phpcs:disable Squiz.Commenting
+		$data_store = new class($data) {
+			private $data;
+			public $created_data = null;
+
+			public function __construct( $data ) {
+				$this->data = $data;
+			}
+
+			public function get_downloads( $params ) {
+				if ( array_key_exists( $params['product_id'], $this->data ) ) {
+					return $this->data[ $params['product_id'] ];
+				} else {
+					return array();
+				}
+			}
+
+			public function create_from_data( $data ) {
+				$this->created_data = $data;
+			}
+		};
+		// phpcs:enable Squiz.Commenting
+
+		$this->register_legacy_proxy_class_mocks(
+			array(
+				'WC_Data_Store' => $data_store,
+			)
+		);
+
+		return $data_store;
+	}
+}

tests/php/src/Proxies/LegacyProxyTest.php

@@ -60,6 +60,18 @@ class LegacyProxyTest extends \WC_Unit_Test_Case {
 		$this->assertEquals( array( 'foo', 'bar' ), \ClassWithSingleton::$instance_args );
 	}
 
+	/**
+	 * @testdox 'get_instance_of' uses the 'load' static method in classes that implement it, passing the supplied arguments.
+	 */
+	public function test_get_instance_of_class_with_load_method_gets_an_instance_of_the_appropriate_class() {
+		// ClassWithLoadMethod is in the root namespace and thus can't be autoloaded.
+		require_once dirname( __DIR__ ) . '/Internal/DependencyManagement/ExampleClasses/ClassWithLoadMethod.php';
+
+		$loaded = $this->sut->get_instance_of( \ClassWithLoadMethod::class, 'foo', 'bar' );
+		$this->assertSame( \ClassWithLoadMethod::$loaded, $loaded );
+		$this->assertEquals( array( 'foo', 'bar' ), \ClassWithLoadMethod::$loaded_args );
+	}
+
 	/**
 	 * @testdox 'get_instance_of' can be used to get an instance of a class implementing WC_Queue_Interface.
 	 */