From 368d6ba1909abe2b83e7df29cccd1efa02e71218 Mon Sep 17 00:00:00 2001
From: "Dominik Schilling (ocean90)" <ocean90@git.wordpress.org>
Date: Wed, 26 Oct 2016 14:14:44 +0000
Subject: [PATCH] I18N: Add `$user_id` argument to `get_user_locale()`.

This allows to retrieve the locale of any user with the additional fallback to the site locale.

Fixes #38512.
See #29783, #26511.

git-svn-id: https://develop.svn.wordpress.org/trunk@38955 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/l10n.php                   | 22 ++++++---
 tests/phpunit/tests/l10n/getUserLocale.php | 52 ++++++++++++++++++++++
 2 files changed, 69 insertions(+), 5 deletions(-)

diff --git a/src/wp-includes/l10n.php b/src/wp-includes/l10n.php
index 03a7a11bec..ba696ded93 100644
--- a/src/wp-includes/l10n.php
+++ b/src/wp-includes/l10n.php
@@ -76,20 +76,32 @@ function get_locale() {
 }
 
 /**
- * Retrieves the locale of the current user.
+ * Retrieves the locale of a user.
  *
  * If the user has a locale set to a non-empty string then it will be
  * returned. Otherwise it returns the locale of get_locale().
  *
  * @since 4.7.0
  *
- * @return string The locale of the current user.
+ * @param int|WP_User $user_id User's ID or a WP_User object. Defaults to current user.
+ * @return string The locale of the user.
  */
-function get_user_locale() {
-	$user = wp_get_current_user();
+function get_user_locale( $user_id = 0 ) {
+	$user = false;
+	if ( 0 === $user_id ) {
+		$user = wp_get_current_user();
+	} elseif ( $user_id instanceof WP_User ) {
+		$user = $user_id;
+	} elseif ( is_numeric( $user_id ) ) {
+		$user = get_user_by( 'id', $user_id );
+	}
+
+	if ( ! $user ) {
+		return get_locale();
+	}
 
 	$locale = $user->locale;
-	return ( '' === $locale ) ? get_locale() : $locale;
+	return $locale ? $locale : get_locale();
 }
 
 /**
diff --git a/tests/phpunit/tests/l10n/getUserLocale.php b/tests/phpunit/tests/l10n/getUserLocale.php
index 1ea3d4b89a..c55642622c 100644
--- a/tests/phpunit/tests/l10n/getUserLocale.php
+++ b/tests/phpunit/tests/l10n/getUserLocale.php
@@ -43,6 +43,11 @@ class Tests_Get_User_Locale extends WP_UnitTestCase {
 		$this->assertSame( get_locale(), get_user_locale() );
 	}
 
+	public function test_returns_site_locale_if_no_user() {
+		wp_set_current_user( 0 );
+		$this->assertSame( get_locale(), get_user_locale() );
+	}
+
 	public function test_returns_correct_user_locale() {
 		set_current_screen( 'dashboard' );
 		$this->assertSame( 'de_DE', get_user_locale() );
@@ -75,4 +80,51 @@ class Tests_Get_User_Locale extends WP_UnitTestCase {
 		$this->assertSame( 'de_DE', $user_locale );
 		$this->assertSame( $user_locale, $user_locale_2 );
 	}
+
+	public function test_user_id_argument_with_id() {
+		$user_id = $this->factory()->user->create( array(
+			'locale' => 'es_ES',
+		) );
+
+		$user_locale1 = get_user_locale( $user_id );
+
+		delete_user_meta( $user_id, 'locale' );
+
+		$user_locale2 = get_user_locale( $user_id );
+
+		$this->assertSame( 'es_ES', $user_locale1 );
+		$this->assertSame( get_locale(), $user_locale2 );
+	}
+
+	public function test_user_id_argument_with_wp_user_object() {
+		$user_id = $this->factory()->user->create( array(
+			'locale' => 'es_ES',
+		) );
+
+		$user = get_user_by( 'id', $user_id );
+
+		$user_locale1 = get_user_locale( $user );
+
+		delete_user_meta( $user_id, 'locale' );
+
+		$user_locale2 = get_user_locale( $user );
+
+		$this->assertSame( 'es_ES', $user_locale1 );
+		$this->assertSame( get_locale(), $user_locale2 );
+	}
+
+	public function test_user_id_argument_with_nonexistent_user() {
+		global $wpdb;
+
+		$user_id = $wpdb->get_var( "SELECT MAX(ID) FROM $wpdb->users" ) + 1;
+
+		$user_locale = get_user_locale( $user_id );
+
+		$this->assertSame( get_locale(), $user_locale );
+	}
+
+	public function test_user_id_argument_with_invalid_type() {
+		$user_locale = get_user_locale( 'string' );
+		$this->assertSame( get_locale(), $user_locale );
+	}
 }