Ticket #26511: 26511.18.1.diff

src/wp-admin/includes/ms.php

@@ -272 +272 @@
         );
         update_option( 'adminhash', $new_admin_email );
 
+        $switched_locale = switch_to_locale( get_user_locale() );
+
         /* translators: Do not translate USERNAME, ADMIN_URL, EMAIL, SITENAME, SITEURL: those are placeholders. */
         $email_text = __( 'Howdy ###USERNAME###,
 
@@ -315 +317 @@
         $content = str_replace( '###SITEURL###', network_home_url(), $content );
 
         wp_mail( $value, sprintf( __( '[%s] New Admin Email Address' ), wp_specialchars_decode( get_option( 'blogname' ) ) ), $content );
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
 }
 
 /**
@@ -353 +359 @@
                 );
                 update_user_meta( $current_user->ID, '_new_email', $new_user_email );
 
+                $switched_locale = switch_to_locale( get_user_locale() );
+
                 /* translators: Do not translate USERNAME, ADMIN_URL, EMAIL, SITENAME, SITEURL: those are placeholders. */
                 $email_text = __( 'Howdy ###USERNAME###,
 
@@ -395 +403 @@
 
                 wp_mail( $_POST['email'], sprintf( __( '[%s] New Email Address' ), wp_specialchars_decode( get_option( 'blogname' ) ) ), $content );
                 $_POST['email'] = $current_user->user_email;
+
+                if ( $switched_locale ) {
+                        restore_previous_locale();
+                }
         }
 }
 

src/wp-admin/includes/upgrade.php

@@ -372 +372 @@
         $email = $user->user_email;
         $name = $user->user_login;
         $login_url = wp_login_url();
+
+        $switched_locale = switch_to_locale( $user->locale );
+
         $message = sprintf( __( "Your new WordPress site has been successfully set up at:
 
 %1\$s
@@ -389 +392 @@
 "), $blog_url, $name, $password, $login_url );
 
         @wp_mail($email, __('New WordPress Site'), $message);
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
 }
 endif;
 

src/wp-admin/ms-delete-site.php

@@ -42 +42 @@
 
         $url_delete = esc_url( admin_url( 'ms-delete-site.php?h=' . $hash ) );
 
+        $switched_locale = switch_to_locale( get_locale() );
+
         /* translators: Do not translate USERNAME, URL_DELETE, SITE_NAME: those are placeholders. */
         $content = __( "Howdy ###USERNAME###,
 
@@ -73 +75 @@
         $content = str_replace( '###SITE_NAME###', get_network()->site_name, $content );
 
         wp_mail( get_option( 'admin_email' ), "[ " . wp_specialchars_decode( get_option( 'blogname' ) ) . " ] ".__( 'Delete My Site' ), $content );
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
         ?>
 
         <p><?php _e( 'Thank you. Please check your email for a link to confirm your action. Your site will not be deleted until this link is clicked.' ) ?></p>

src/wp-admin/user-new.php

@@ -87 +87 @@
                          */
                         do_action( 'invite_user', $user_id, $role, $newuser_key );
 
+                        $switched_locale = switch_to_locale( $user_details->locale );
+
                         /* translators: 1: Site name, 2: site URL, 3: role, 4: activation URL */
                         $message = __( 'Hi,
 
@@ -96 +98 @@
 Please click the following link to confirm the invite:
 %4$s' );
                         wp_mail( $new_user_email, sprintf( __( '[%s] Joining confirmation' ), wp_specialchars_decode( get_option( 'blogname' ) ) ), sprintf( $message, get_option( 'blogname' ), home_url(), wp_specialchars_decode( translate_user_role( $role['name'] ) ), home_url( "/newbloguser/$newuser_key/" ) ) );
+
+                        if ( $switched_locale ) {
+                                restore_previous_locale();
+                        }
+
                         $redirect = add_query_arg( array('update' => 'add'), 'user-new.php' );
                 }
         }

src/wp-includes/class-wp-locale-switcher.php

@@ +1 @@
+<?php
+/**
+ * Locale API: WP_Locale_Switcher class
+ *
+ * @package WordPress
+ * @subpackage i18n
+ * @since 4.7.0
+ */
+
+/**
+ * Core class used for switching locales.
+ *
+ * @since 4.7.0
+ */
+class WP_Locale_Switcher {
+        /**
+         * Locale stack.
+         *
+         * @since 4.7.0
+         * @access private
+         * @var string[]
+         */
+        private $locales = array();
+
+        /**
+         * Original locale.
+         *
+         * @since 4.7.0
+         * @access private
+         * @var string
+         */
+        private $original_locale;
+
+        /**
+         * Holds all available languages.
+         *
+         * @since 4.7.0
+         * @access private
+         * @var array An array of language codes (file names without the .mo extension).
+         */
+        private $available_languages = array();
+
+        /**
+         * Constructor.
+         *
+         * Stores the original locale as well as a list of all available languages.
+         *
+         * @since 4.7.0
+         */
+        public function __construct() {
+                $this->original_locale     = is_admin() ? get_user_locale() : get_locale();
+                $this->available_languages = array_merge( array( 'en_US' ), get_available_languages() );
+        }
+
+        /**
+         * Initializes the locale switcher.
+         *
+         * Hooks into the {@see 'locale'} filter to change the locale on the fly.
+         */
+        public function init() {
+                add_filter( 'locale', array( $this, 'filter_locale' ) );
+        }
+
+        /**
+         * Switches the translations according to the given locale.
+         *
+         * @since 4.7.0
+         *
+         * @param string $locale The locale to switch to.
+         * @return bool True on success, false on failure.
+         */
+        public function switch_to_locale( $locale ) {
+                $current_locale = is_admin() ? get_user_locale() : get_locale();
+                if ( $current_locale === $locale ) {
+                        return false;
+                }
+
+                if ( ! in_array( $locale, $this->available_languages, true ) ) {
+                        return false;
+                }
+
+                $this->locales[] = $locale;
+
+                $this->change_locale( $locale );
+
+                /**
+                 * Fires when the locale is switched.
+                 *
+                 * @since 4.7.0
+                 *
+                 * @param string $locale The new locale.
+                 */
+                do_action( 'switch_locale', $locale );
+
+                return true;
+        }
+
+        /**
+         * Restores the translations according to the previous locale.
+         *
+         * @since 4.7.0
+         *
+         * @return string|false Locale on success, false on failure.
+         */
+        public function restore_previous_locale() {
+                $previous_locale = array_pop( $this->locales );
+
+                if ( null === $previous_locale ) {
+                        // The stack is empty, bail.
+                        return false;
+                }
+
+                $locale = end( $this->locales );
+
+                if ( ! $locale ) {
+                        // There's nothing left in the stack: go back to the original locale.
+                        $locale = $this->original_locale;
+                }
+
+                $this->change_locale( $locale );
+
+                /**
+                 * Fires when the locale is restored to the previous one.
+                 *
+                 * @since 4.7.0
+                 *
+                 * @param string $locale          The new locale.
+                 * @param string $previous_locale The previous locale.
+                 */
+                do_action( 'restore_previous_locale', $locale, $previous_locale );
+
+                return $locale;
+        }
+
+        /**
+         * Restores the translations according to the original locale.
+         *
+         * @since 4.7.0
+         *
+         * @return string|false Locale on success, false on failure.
+         */
+        public function restore_current_locale() {
+                if ( empty( $this->locales ) ) {
+                        return false;
+                }
+
+                $this->locales = array( $this->original_locale );
+
+                return $this->restore_previous_locale();
+        }
+
+        /**
+         * Whether switch_to_locale() is in effect.
+         *
+         * @since 4.7.0
+         *
+         * @return bool True if the locale has been switched, false otherwise.
+         */
+        public function is_switched() {
+                return ! empty( $this->locales );
+        }
+
+        /**
+         * Filters the WordPress install's locale.
+         *
+         * @since 4.7.0
+         *
+         * @param string $locale The WordPress install's locale.
+         * @return string The locale currently being switched to.
+         */
+        public function filter_locale( $locale ) {
+                $switched_locale = end( $this->locales );
+
+                if ( $switched_locale ) {
+                        return $switched_locale;
+                }
+
+                return $locale;
+        }
+
+        /**
+         * Load translations for a given locale.
+         *
+         * When switching to a locale, translations for this locale must be loaded from scratch.
+         *
+         * @since 4.7.0
+         * @access private
+         *
+         * @global Mo[] $l10n An array of all currently loaded text domains.
+         *
+         * @param string $locale The locale to load translations for.
+         */
+        private function load_translations( $locale ) {
+                global $l10n;
+
+                $domains = $l10n ? array_keys( $l10n ) : array();
+
+                load_default_textdomain( $locale );
+
+                foreach ( $domains as $domain ) {
+                        if ( 'default' === $domain ) {
+                                continue;
+                        }
+
+                        $mofile = $l10n[ $domain ]->get_filename();
+
+                        unload_textdomain( $domain );
+
+                        if ( $mofile ) {
+                                load_textdomain( $domain, $mofile );
+                        }
+
+                        get_translations_for_domain( $domain );
+                }
+        }
+
+        /**
+         * Changes the site's locale to the given one.
+         *
+         * Loads the translations, changes the global `$wp_locale` object and updates
+         * all post type labels.
+         *
+         * @since 4.7.0
+         * @access private
+         *
+         * @global WP_Locale $wp_locale The WordPress date and time locale object.
+         *
+         * @param string $locale The locale to change to.
+         */
+        private function change_locale( $locale ) {
+                $this->load_translations( $locale );
+
+                $GLOBALS['wp_locale'] = new WP_Locale();
+
+                /**
+                 * Fires when the locale is switched to or restored.
+                 *
+                 * @since 4.7.0
+                 *
+                 * @param string $locale The new locale.
+                 */
+                do_action( 'change_locale', $locale );
+        }
+}

src/wp-includes/default-filters.php

@@ -406 +406 @@
 add_action( 'admin_menu', '_add_post_type_submenus' );
 add_action( 'before_delete_post', '_reset_front_page_settings_for_post' );
 add_action( 'wp_trash_post',      '_reset_front_page_settings_for_post' );
+add_action( 'change_locale', 'create_initial_post_types' );
 
 // Post Formats
 add_filter( 'request', '_post_format_request' );
@@ -431 +432 @@
 
 // Taxonomy
 add_action( 'init', 'create_initial_taxonomies', 0 ); // highest priority
+add_action( 'change_locale', 'create_initial_taxonomies' );
 
 // Canonical
 add_action( 'template_redirect', 'redirect_canonical' );

src/wp-includes/l10n.php

@@ -1166 +1166 @@
         }
         return $wp_locale->is_rtl();
 }
+
+/**
+ * Switches the translations according to the given locale.
+ *
+ * @since 4.7.0
+ *
+ * @global WP_Locale_Switcher $wp_locale_switcher
+ *
+ * @param string $locale The locale.
+ * @return bool True on success, false on failure.
+ */
+function switch_to_locale( $locale ) {
+        /* @var WP_Locale_Switcher $wp_locale_switcher */
+        global $wp_locale_switcher;
+
+        return $wp_locale_switcher->switch_to_locale( $locale );
+}
+
+/**
+ * Restores the translations according to the previous locale.
+ *
+ * @since 4.7.0
+ *
+ * @global WP_Locale_Switcher $wp_locale_switcher
+ *
+ * @return string|false Locale on success, false on error.
+ */
+function restore_previous_locale() {
+        /* @var WP_Locale_Switcher $wp_locale_switcher */
+        global $wp_locale_switcher;
+
+        return $wp_locale_switcher->restore_previous_locale();
+}
+
+/**
+ * Restores the translations according to the original locale.
+ *
+ * @since 4.7.0
+ *
+ * @global WP_Locale_Switcher $wp_locale_switcher
+ *
+ * @return string|false Locale on success, false on error.
+ */
+function restore_current_locale() {
+        /* @var WP_Locale_Switcher $wp_locale_switcher */
+        global $wp_locale_switcher;
+
+        return $wp_locale_switcher->restore_current_locale();
+}
+
+/**
+ * Whether switch_to_locale() is in effect.
+ *
+ * @since 4.7.0
+ *
+ * @global WP_Locale_Switcher $wp_locale_switcher
+ *
+ * @return bool True if the locale has been switched, false otherwise.
+ */
+function is_locale_switched() {
+        /* @var WP_Locale_Switcher $wp_locale_switcher */
+        global $wp_locale_switcher;
+
+        return $wp_locale_switcher->is_switched();
+}

src/wp-includes/load.php

@@ -841 +841 @@
  * @since 3.4.0
  * @access private
  *
- * @global string    $text_direction
- * @global WP_Locale $wp_locale      The WordPress date and time locale object.
+ * @global string             $text_direction
+ * @global WP_Locale          $wp_locale      The WordPress date and time locale object.
+ * @global WP_Locale_Switcher $wp_locale_switcher WordPress locale switcher object.
  *
  * @staticvar bool $loaded
  */
 function wp_load_translations_early() {
-        global $text_direction, $wp_locale;
+        global $text_direction, $wp_locale, $wp_locale_switcher;
 
         static $loaded = false;
         if ( $loaded )
@@ -864 +865 @@
         require_once ABSPATH . WPINC . '/pomo/mo.php';
         require_once ABSPATH . WPINC . '/l10n.php';
         require_once ABSPATH . WPINC . '/class-wp-locale.php';
+        require_once ABSPATH . WPINC . '/class-wp-locale-switcher.php';
 
         // General libraries
         require_once ABSPATH . WPINC . '/plugin.php';
@@ -915 +917 @@
         }
 
         $wp_locale = new WP_Locale();
+        $wp_locale_switcher = new WP_Locale_Switcher();
+        $wp_locale_switcher->init();
 }
 
 /**

src/wp-includes/ms-functions.php

@@ -800 +800 @@
                 $admin_email = 'support@' . $_SERVER['SERVER_NAME'];
         $from_name = get_site_option( 'site_name' ) == '' ? 'WordPress' : esc_html( get_site_option( 'site_name' ) );
         $message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . "Content-Type: text/plain; charset=\"" . get_option('blog_charset') . "\"\n";
+
+        $user = get_user_by( 'login', $user );
+        $switched_locale = switch_to_locale( $user && $user->locale ? $user->locale : get_locale() );
+
         $message = sprintf(
                 /**
                  * Filters the message content of the new blog notification email.
@@ -849 +853 @@
                 esc_url( 'http://' . $domain . $path )
         );
         wp_mail( $user_email, wp_specialchars_decode( $subject ), $message, $message_headers );
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
+
         return true;
 }
 
@@ -887 +896 @@
         if ( ! apply_filters( 'wpmu_signup_user_notification', $user, $user_email, $key, $meta ) )
                 return false;
 
+        $user = get_user_by( 'login', $user );
+        $switched_locale = switch_to_locale( $user && $user->locale ? $user->locale : get_locale() );
+
         // Send email with activation link.
         $admin_email = get_site_option( 'admin_email' );
         if ( $admin_email == '' )
@@ -934 +946 @@
                 $user
         );
         wp_mail( $user_email, wp_specialchars_decode( $subject ), $message, $message_headers );
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
+
         return true;
 }
 
@@ -1448 +1465 @@
         if ( ! apply_filters( 'wpmu_welcome_notification', $blog_id, $user_id, $password, $title, $meta ) )
                 return false;
 
+        $user = get_userdata( $user_id );
+
+        $switched_locale = switch_to_locale( $user->locale );
+
         $welcome_email = get_site_option( 'welcome_email' );
         if ( $welcome_email == false ) {
                 /* translators: Do not translate USERNAME, SITE_NAME, BLOG_URL, PASSWORD: those are placeholders. */
@@ -1468 +1489 @@
         }
 
         $url = get_blogaddress_by_id($blog_id);
-        $user = get_userdata( $user_id );
 
         $welcome_email = str_replace( 'SITE_NAME', $current_network->site_name, $welcome_email );
         $welcome_email = str_replace( 'BLOG_TITLE', $title, $welcome_email );
@@ -1512 +1532 @@
          */
         $subject = apply_filters( 'update_welcome_subject', sprintf( __( 'New %1$s Site: %2$s' ), $current_network->site_name, wp_unslash( $title ) ) );
         wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
+
         return true;
 }
 
@@ -1551 +1576 @@
 
         $user = get_userdata( $user_id );
 
+        $switched_locale = switch_to_locale( $user->locale );
+
         /**
          * Filters the content of the welcome email after user activation.
          *
@@ -1590 +1617 @@
          */
         $subject = apply_filters( 'update_welcome_user_subject', sprintf( __( 'New %1$s User: %2$s' ), $current_network->site_name, $user->user_login) );
         wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
+
         return true;
 }
 

src/wp-includes/pluggable.php

@@ -211 +211 @@
         // (Re)create it, if it's gone missing
         if ( ! ( $phpmailer instanceof PHPMailer ) ) {
                 require_once ABSPATH . WPINC . '/class-phpmailer.php';
-                require_once ABSPATH . WPINC . '/class-smtp.php'; 
+                require_once ABSPATH . WPINC . '/class-smtp.php';
                 $phpmailer = new PHPMailer( true );
         }
 
@@ -1418 +1418 @@
                 $emails = array_flip( $emails );
         }
 
+        $switched_locale = switch_to_locale( get_locale() );
+
         $comment_author_domain = @gethostbyaddr($comment->comment_author_IP);
 
         // The blogname option is escaped with esc_html on the way into the database in sanitize_option
@@ -1522 +1524 @@
                 @wp_mail( $email, wp_specialchars_decode( $subject ), $notify_message, $message_headers );
         }
 
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
+
         return true;
 }
 endif;
@@ -1569 +1575 @@
                         $emails[] = $user->user_email;
         }
 
+        $switched_locale = switch_to_locale( get_locale() );
+
         $comment_author_domain = @gethostbyaddr($comment->comment_author_IP);
         $comments_waiting = $wpdb->get_var("SELECT count(comment_ID) FROM $wpdb->comments WHERE comment_approved = '0'");
 
@@ -1664 +1672 @@
                 @wp_mail( $email, wp_specialchars_decode( $subject ), $notify_message, $message_headers );
         }
 
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
+
         return true;
 }
 endif;
@@ -1723 +1735 @@
         $blogname = wp_specialchars_decode(get_option('blogname'), ENT_QUOTES);
 
         if ( 'user' !== $notify ) {
+                $switched_locale = switch_to_locale( get_locale() );
                 $message  = sprintf( __( 'New user registration on your site %s:' ), $blogname ) . "\r\n\r\n";
                 $message .= sprintf( __( 'Username: %s' ), $user->user_login ) . "\r\n\r\n";
                 $message .= sprintf( __( 'Email: %s' ), $user->user_email ) . "\r\n";
 
                 @wp_mail( get_option( 'admin_email' ), sprintf( __( '[%s] New User Registration' ), $blogname ), $message );
+
+                if ( $switched_locale ) {
+                        restore_previous_locale();
+                }
         }
 
         // `$deprecated was pre-4.3 `$plaintext_pass`. An empty `$plaintext_pass` didn't sent a user notifcation.
@@ -1748 +1765 @@
         $hashed = time() . ':' . $wp_hasher->HashPassword( $key );
         $wpdb->update( $wpdb->users, array( 'user_activation_key' => $hashed ), array( 'user_login' => $user->user_login ) );
 
+        $switched_locale = switch_to_locale( $user->locale );
+
         $message = sprintf(__('Username: %s'), $user->user_login) . "\r\n\r\n";
         $message .= __('To set your password, visit the following address:') . "\r\n\r\n";
         $message .= '<' . network_site_url("wp-login.php?action=rp&key=$key&login=" . rawurlencode($user->user_login), 'login') . ">\r\n\r\n";
@@ -1755 +1774 @@
         $message .= wp_login_url() . "\r\n";
 
         wp_mail($user->user_email, sprintf(__('[%s] Your username and password info'), $blogname), $message);
+
+        if ( $switched_locale ) {
+                restore_previous_locale();
+        }
 }
 endif;
 

src/wp-includes/pomo/mo.php

@@ -16 +16 @@
         var $_nplurals = 2;
 
         /**
+         * Loaded MO file.
+         *
+         * @var string
+         */
+        private $filename = '';
+
+        /**
+         * Returns the loaded MO file.
+         *
+         * @return string The loaded MO file.
+         */
+        public function get_filename() {
+                return $this->filename;
+        }
+
+        /**
          * Fills up with the entries from MO file $filename
          *
          * @param string $filename MO file to load
          */
         function import_from_file($filename) {
-                $reader = new POMO_FileReader($filename);
-                if (!$reader->is_resource())
+                $reader = new POMO_FileReader( $filename );
+
+                if ( ! $reader->is_resource() ) {
                         return false;
-                return $this->import_from_reader($reader);
+                }
+
+                $this->filename = (string) $filename;
+
+                return $this->import_from_reader( $reader );
         }
 
         /**
@@ -299 +320 @@
                 return $this->_nplurals;
         }
 }
-endif;
- No newline at end of file
+endif;

src/wp-includes/user.php

@@ -1801 +1801 @@
 
                 $blog_name = wp_specialchars_decode( get_option( 'blogname' ), ENT_QUOTES );
 
+                $switched_locale = false;
+                if ( ! empty( $send_password_change_email ) || ! empty( $send_email_change_email ) ) {
+                        $switched_locale = switch_to_locale( isset( $user['locale'] ) ? $user['locale'] : get_locale() );
+                }
+
                 if ( ! empty( $send_password_change_email ) ) {
-
                         /* translators: Do not translate USERNAME, ADMIN_EMAIL, EMAIL, SITENAME, SITEURL: those are placeholders. */
                         $pass_change_text = __( 'Hi ###USERNAME###,
 
@@ -1910 +1914 @@
 
                         wp_mail( $email_change_email['to'], sprintf( $email_change_email['subject'], $blog_name ), $email_change_email['message'], $email_change_email['headers'] );
                 }
+
+                if ( $switched_locale ) {
+                        restore_previous_locale();
+                }
         }
 
         // Update the cookies if the password changed.

src/wp-settings.php

@@ -130 +130 @@
 // Load the L10n library.
 require_once( ABSPATH . WPINC . '/l10n.php' );
 require_once( ABSPATH . WPINC . '/class-wp-locale.php' );
+require_once( ABSPATH . WPINC . '/class-wp-locale-switcher.php' );
 
 // Run the installer if WordPress is not installed.
 wp_not_installed();
@@ -400 +401 @@
  */
 $GLOBALS['wp_locale'] = new WP_Locale();
 
+/**
+ *  WordPress Locale Switcher object for switching locales.
+ *
+ * @since 4.7.0
+ *
+ * @global WP_Locale_Switcher $wp_locale_switcher WordPress locale switcher object.
+ */
+$GLOBALS['wp_locale_switcher'] = new WP_Locale_Switcher();
+$GLOBALS['wp_locale_switcher']->init();
+
 // Load the functions for the active theme, for both parent and child theme if applicable.
 if ( ! wp_installing() || 'wp-activate.php' === $pagenow ) {
         if ( TEMPLATEPATH !== STYLESHEETPATH && file_exists( STYLESHEETPATH . '/functions.php' ) )

tests/phpunit/tests/l10n/loadTextdomainJustInTime.php

@@ -9 +9 @@
         private $orig_theme_dir;
         private $theme_root;
 
-        function setUp() {
+        public function setUp() {
                 parent::setUp();
 
                 $this->theme_root = DIR_TESTDATA . '/themedir1';
@@ -22 +22 @@
                 add_filter( 'template_root', array( $this, 'filter_theme_root' ) );
                 wp_clean_themes_cache();
                 unset( $GLOBALS['wp_themes'] );
-
+                unset( $GLOBALS['l10n'] );
                 unset( $GLOBALS['l10n_unloaded'] );
         }
 
-        function tearDown() {
+        public function tearDown() {
                 $GLOBALS['wp_theme_directories'] = $this->orig_theme_dir;
                 remove_filter( 'theme_root', array( $this, 'filter_theme_root' ) );
                 remove_filter( 'stylesheet_root', array( $this, 'filter_theme_root' ) );
@@ -33 +33 @@
                 remove_filter( 'template_root', array( $this, 'filter_theme_root' ) );
                 wp_clean_themes_cache();
                 unset( $GLOBALS['wp_themes'] );
+                unset( $GLOBALS['l10n'] );
+                unset( $GLOBALS['l10n_unloaded'] );
 
                 parent::tearDown();
         }
@@ -60 +62 @@
                 $expected_output             = i18n_plugin_test();
                 $is_textdomain_loaded_after  = is_textdomain_loaded( 'internationalized-plugin' );
 
-                unload_textdomain( 'internationalized-plugin' );
                 remove_filter( 'locale', array( $this, 'filter_set_locale_to_german' ) );
 
                 $this->assertFalse( $is_textdomain_loaded_before );
@@ -82 +83 @@
                 $expected_output             = i18n_theme_test();
                 $is_textdomain_loaded_after  = is_textdomain_loaded( 'internationalized-theme' );
 
-                unload_textdomain( 'internationalized-theme' );
                 remove_filter( 'locale', array( $this, 'filter_set_locale_to_german' ) );
 
                 $this->assertFalse( $is_textdomain_loaded_before );
@@ -141 +141 @@
                 $this->assertSame( 'Das ist ein Dummy Plugin', $expected_output_final );
                 $this->assertTrue( $is_textdomain_loaded_final );
         }
+
+        /**
+         * @ticket 26511
+         */
+        public function test_plugin_translation_after_switching_locale() {
+                require_once DIR_TESTDATA . '/plugins/internationalized-plugin.php';
+
+                switch_to_locale( 'de_DE' );
+                $expected = i18n_plugin_test();
+                restore_previous_locale();
+
+                $this->assertSame( 'Das ist ein Dummy Plugin', $expected );
+        }
+
+        /**
+         * @ticket 26511
+         */
+        public function test_theme_translation_after_switching_locale() {
+                switch_theme( 'internationalized-theme' );
+
+                require_once get_stylesheet_directory() . '/functions.php';
+
+                switch_to_locale( 'de_DE' );
+                $expected = i18n_theme_test();
+                restore_previous_locale();
+
+                switch_theme( WP_DEFAULT_THEME );
+
+                $this->assertSame( 'Das ist ein Dummy Theme', $expected );
+        }
 }

tests/phpunit/tests/l10n/localeSwitcher.php

@@ +1 @@
+<?php
+
+/**
+ * @group l10n
+ * @group i18n
+ * @group 26511
+ */
+class Tests_Locale_Switcher extends WP_UnitTestCase {
+        /**
+         * @var string
+         */
+        protected $locale = '';
+
+        /**
+         * @var string
+         */
+        protected $previous_locale = '';
+
+        public function setUp() {
+                parent::setUp();
+
+                $this->locale = '';
+                $this->previous_locale = '';
+
+                unset( $GLOBALS['l10n'] );
+                unset( $GLOBALS['l10n_unloaded'] );
+        }
+
+        public function tearDown() {
+                unset( $GLOBALS['l10n'] );
+                unset( $GLOBALS['l10n_unloaded'] );
+
+                parent::tearDown();
+        }
+
+        public function test_switch_to_non_existent_locale_returns_false() {
+                $this->assertFalse( switch_to_locale( 'foo_BAR' ) );
+        }
+
+        public function test_switch_to_non_existent_locale_does_not_change_locale() {
+                switch_to_locale( 'foo_BAR' );
+
+                $this->assertSame( 'en_US', get_locale() );
+        }
+
+        public function test_switch_to_locale_returns_true() {
+                $expected = switch_to_locale( 'en_GB' );
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertTrue( $expected );
+        }
+
+        public function test_switch_to_locale_changes_the_locale() {
+                switch_to_locale( 'en_GB' );
+
+                $locale = get_locale();
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertSame( 'en_GB', $locale );
+        }
+
+        public function test_switch_to_locale_loads_translation() {
+                switch_to_locale( 'es_ES' );
+
+                $actual = __( 'Invalid parameter.' );
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertSame( 'Parámetro no válido. ', $actual );
+        }
+
+        public function test_switch_to_locale_changes_wp_locale_global() {
+                global $wp_locale;
+
+                $expected = array(
+                        'thousands_sep' => '.',
+                        'decimal_point' => ',',
+                );
+
+                switch_to_locale( 'de_DE' );
+
+                $wp_locale_de_DE = clone $wp_locale;
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertEqualSetsWithIndex( $expected, $wp_locale_de_DE->number_format );
+        }
+
+        public function test_switch_to_locale_en_US() {
+                switch_to_locale( 'en_GB' );
+                $locale_en_GB = get_locale();
+                switch_to_locale( 'en_US' );
+                $locale_en_US = get_locale();
+
+                // Cleanup.
+                restore_current_locale();
+
+                $this->assertSame( 'en_GB', $locale_en_GB );
+                $this->assertSame( 'en_US', $locale_en_US );
+        }
+
+        public function test_switch_to_locale_multiple_times() {
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( 'es_ES' );
+                $locale = get_locale();
+
+                // Cleanup.
+                restore_previous_locale();
+                restore_previous_locale();
+
+                $this->assertSame( 'es_ES', $locale );
+        }
+
+        public function test_switch_to_locale_multiple_times_loads_translation() {
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( 'de_DE' );
+                switch_to_locale( 'es_ES' );
+
+                $actual = __( 'Invalid parameter.' );
+
+                // Cleanup.
+                restore_previous_locale();
+                restore_previous_locale();
+                restore_previous_locale();
+
+                $this->assertSame( 'Parámetro no válido. ', $actual );
+        }
+
+        public function test_restore_previous_locale_without_switching() {
+                $this->assertFalse( restore_previous_locale() );
+        }
+
+        public function test_restore_previous_locale_changes_the_locale_back() {
+                switch_to_locale( 'en_GB' );
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertSame( 'en_US', get_locale() );
+        }
+
+        public function test_restore_previous_locale_after_switching_multiple_times() {
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( 'es_ES' );
+                restore_previous_locale();
+
+                $locale = get_locale();
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertSame( 'en_GB', $locale );
+        }
+
+        public function test_restore_previous_locale_restores_translation() {
+                switch_to_locale( 'es_ES' );
+                restore_previous_locale();
+
+                $actual = __( 'Invalid parameter.' );
+
+                $this->assertSame( 'Invalid parameter.', $actual );
+        }
+
+        public function test_restore_previous_locale_action_passes_previous_locale() {
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( 'es_ES' );
+
+                add_action( 'restore_previous_locale', array( $this, 'store_locale' ), 10, 2 );
+
+                restore_previous_locale();
+
+                $previous_locale = $this->previous_locale;
+
+                // Cleanup.
+                restore_previous_locale();
+
+                $this->assertSame( 'es_ES', $previous_locale );
+        }
+
+        public function test_restore_previous_locale_restores_wp_locale_global() {
+                global $wp_locale;
+
+                $expected = array(
+                        'thousands_sep' => ',',
+                        'decimal_point' => '.',
+                );
+
+                switch_to_locale( 'de_DE' );
+                restore_previous_locale();
+
+                $this->assertEqualSetsWithIndex( $expected, $wp_locale->number_format );
+        }
+
+        public function test_restore_current_locale_without_switching() {
+                $this->assertFalse( restore_current_locale() );
+        }
+
+        public function test_restore_current_locale_after_switching_multiple_times() {
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( 'nl_NL' );
+                switch_to_locale( 'es_ES' );
+
+                restore_current_locale();
+
+                $this->assertSame( 'en_US', get_locale() );
+        }
+
+        public function store_locale( $locale, $previous_locale ) {
+                $this->locale = $locale;
+                $this->previous_locale = $previous_locale;
+        }
+
+        public function test_is_locale_switched_if_not_switched() {
+                $this->assertFalse( is_locale_switched() );
+        }
+
+        public function test_is_locale_switched_original_locale() {
+                $original_locale = get_locale();
+
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( $original_locale );
+
+                $is_locale_switched = is_locale_switched();
+
+                restore_current_locale();
+
+                $this->assertTrue( $is_locale_switched );
+        }
+
+        public function test_is_locale_switched() {
+                switch_to_locale( 'en_GB' );
+                switch_to_locale( 'nl_NL' );
+
+                $is_locale_switched = is_locale_switched();
+
+                restore_current_locale();
+
+                $this->assertTrue( $is_locale_switched );
+        }
+
+        public function test_switch_to_site_locale_if_user_locale_is_set() {
+                global $l10n, $wp_locale_switcher;
+
+                $site_locale = get_locale();
+
+                $user_id = $this->factory()->user->create( array(
+                        'role'   => 'administrator',
+                        'locale' => 'de_DE',
+                ) );
+
+                wp_set_current_user( $user_id );
+                set_current_screen( 'dashboard' );
+
+                $locale_switcher = clone $wp_locale_switcher;
+
+                $wp_locale_switcher = new WP_Locale_Switcher();
+                $wp_locale_switcher->init();
+
+                $user_locale = get_user_locale();
+
+                $this->assertSame( 'de_DE', $user_locale );
+
+                load_default_textdomain( $user_locale );
+                $language_header_before_switch = $l10n['default']->headers['Language']; // de_DE
+
+                $locale_switched_user_locale = switch_to_locale( $user_locale ); // False.
+                $locale_switched_site_locale = switch_to_locale( $site_locale ); // True.
+                $site_locale_after_switch = get_locale();
+                $language_header_after_switch = isset( $l10n['default'] ); // en_US
+
+                restore_current_locale();
+
+                $language_header_after_restore = $l10n['default']->headers['Language']; // de_DE
+
+                $wp_locale_switcher = $locale_switcher;
+
+                set_current_screen( 'front' );
+
+                $this->assertFalse( $locale_switched_user_locale );
+                $this->assertTrue( $locale_switched_site_locale );
+                $this->assertSame( $site_locale, $site_locale_after_switch );
+                $this->assertSame( 'de_DE', $language_header_before_switch );
+                $this->assertFalse( $language_header_after_switch );
+                $this->assertSame( 'de_DE', $language_header_after_restore );
+        }
+
+        public function test_switch_to_different_site_locale_if_user_locale_is_set() {
+                global $l10n, $wp_locale_switcher;
+
+                // Change site locale to es_ES.
+                add_filter( 'locale', array( $this, 'filter_locale' ) );
+
+                $site_locale = get_locale();
+
+                $user_id = $this->factory()->user->create( array(
+                        'role'   => 'administrator',
+                        'locale' => 'de_DE',
+                ) );
+
+                wp_set_current_user( $user_id );
+                set_current_screen( 'dashboard' );
+
+                $locale_switcher = clone $wp_locale_switcher;
+
+                $wp_locale_switcher = new WP_Locale_Switcher();
+                $wp_locale_switcher->init();
+
+                $user_locale = get_user_locale();
+
+                $this->assertSame( 'de_DE', $user_locale );
+
+                load_default_textdomain( $user_locale );
+                $language_header_before_switch = $l10n['default']->headers['Language']; // de_DE
+
+                $locale_switched_user_locale = switch_to_locale( $user_locale ); // False.
+                $locale_switched_site_locale = switch_to_locale( $site_locale ); // True.
+                $site_locale_after_switch = get_locale();
+                $language_header_after_switch = $l10n['default']->headers['Language']; // es_ES
+
+                restore_current_locale();
+
+                $language_header_after_restore = $l10n['default']->headers['Language']; // de_DE
+
+                $wp_locale_switcher = $locale_switcher;
+
+                set_current_screen( 'front' );
+
+                remove_filter( 'locale', array( $this, 'filter_locale' ) );
+
+                $this->assertFalse( $locale_switched_user_locale );
+                $this->assertTrue( $locale_switched_site_locale );
+                $this->assertSame( $site_locale, $site_locale_after_switch );
+                $this->assertSame( 'de_DE', $language_header_before_switch );
+                $this->assertSame( 'es_ES', $language_header_after_switch );
+                $this->assertSame( 'de_DE', $language_header_after_restore );
+        }
+
+        public function test_multiple_switches_to_site_locale_and_user_locale() {
+                global $wp_locale_switcher;
+
+                $site_locale = get_locale();
+
+                $user_id = $this->factory()->user->create( array(
+                        'role'   => 'administrator',
+                        'locale' => 'en_GB',
+                ) );
+
+                wp_set_current_user( $user_id );
+                set_current_screen( 'dashboard' );
+
+                $locale_switcher = clone $wp_locale_switcher;
+
+                $wp_locale_switcher = new WP_Locale_Switcher();
+                $wp_locale_switcher->init();
+
+                $user_locale = get_user_locale();
+
+                load_default_textdomain( $user_locale );
+
+                require_once DIR_TESTDATA . '/plugins/internationalized-plugin.php';
+
+                switch_to_locale( 'de_DE' );
+                switch_to_locale( $site_locale );
+
+                $expected = i18n_plugin_test();
+
+                restore_current_locale();
+
+                $wp_locale_switcher = $locale_switcher;
+
+                set_current_screen( 'front' );
+
+                $this->assertSame( 'en_US', get_locale() );
+                $this->assertSame( 'This is a dummy plugin', $expected );
+        }
+
+        public function filter_locale() {
+                return 'es_ES';
+        }
+}

tests/phpunit/tests/locale.php

@@ -1 +1 @@
 <?php
 
 /**
- * @group locale
+ * @group l10n
  * @group i18n
  */
 class Tests_Locale extends WP_UnitTestCase {