IBX-7862: Fixed user setting value

phpstan-baseline.neon

@@ -760,11 +760,6 @@ parameters:
 			count: 1
 			path: src/lib/UserSetting/Setting/FullDateTimeFormat.php
 
-		-
-			message: "#^Method Ibexa\\\\User\\\\UserSetting\\\\Setting\\\\Language\\:\\:getDefaultValue\\(\\) should return string but returns string\\|false\\.$#"
-			count: 1
-			path: src/lib/UserSetting/Setting/Language.php
-
 		-
 			message: "#^Method Ibexa\\\\User\\\\UserSetting\\\\Setting\\\\ShortDateTimeFormat\\:\\:getDefaultValue\\(\\) should return string but returns string\\|null\\.$#"
 			count: 1

src/lib/UserSetting/Setting/Language.php

@@ -72,9 +72,16 @@ public function getDisplayValue(string $storageValue): string
      */
     public function getDefaultValue(): string
     {
+        $defaultLocale = '';
         $preferredLocales = $this->userLanguagePreferenceProvider->getPreferredLocales();
 
-        return reset($preferredLocales);
+        $list = $this->availableLocaleChoiceLoader->getChoiceList();
+        $commonLocales = array_intersect($preferredLocales, $list);
+        if (!empty($commonLocales)) {
+            $defaultLocale = reset($commonLocales);
+        }
+
+        return $defaultLocale;
     }
 
     /**

tests/lib/UserSetting/Setting/LanguageTest.php

@@ -0,0 +1,67 @@
+<?php
+
+/**
+ * @copyright Copyright (C) Ibexa AS. All rights reserved.
+ * @license For full copyright and license information view LICENSE file distributed with this source code.
+ */
+declare(strict_types=1);
+
+namespace Ibexa\Tests\User\UserSetting;
+
+use Ibexa\Core\MVC\Symfony\Locale\UserLanguagePreferenceProviderInterface;
+use Ibexa\User\Form\ChoiceList\Loader\AvailableLocaleChoiceLoader;
+use Ibexa\User\UserSetting\Setting\Language;
+use PHPUnit\Framework\TestCase;
+use Symfony\Contracts\Translation\TranslatorInterface;
+
+final class LanguageTest extends TestCase
+{
+    /** @var \Ibexa\Core\MVC\Symfony\Locale\UserLanguagePreferenceProviderInterface&\PHPUnit\Framework\MockObject\MockObject */
+    private UserLanguagePreferenceProviderInterface $userLanguagePreferenceProvider;
+
+    /** @var \Ibexa\User\Form\ChoiceList\Loader\AvailableLocaleChoiceLoader&\PHPUnit\Framework\MockObject\MockObject */
+    private AvailableLocaleChoiceLoader $availableLocaleChoiceLoader;
+
+    protected function setUp(): void
+    {
+        $this->userLanguagePreferenceProvider = $this->createMock(
+            UserLanguagePreferenceProviderInterface::class
+        );
+        $this->availableLocaleChoiceLoader = $this->createMock(
+            AvailableLocaleChoiceLoader::class
+        );
+    }
+
+    /**
+     * @dataProvider providerForDefaultValue
+     *
+     * @param string[] $availableLocales
+     * @param string[] $preferredLocales
+     */
+    public function testGetDefaultValue(
+        array $preferredLocales,
+        array $availableLocales,
+        string $expectedDefaultValue
+    ): void {
+        $this->userLanguagePreferenceProvider->method('getPreferredLocales')->willReturn($preferredLocales);
+        $this->availableLocaleChoiceLoader->method('getChoiceList')->willReturn($availableLocales);
+
+        $language = new Language(
+            $this->createMock(TranslatorInterface::class),
+            $this->userLanguagePreferenceProvider,
+            $this->availableLocaleChoiceLoader,
+        );
+
+        self::assertSame($expectedDefaultValue, $language->getDefaultValue());
+    }
+
+    /**
+     * @return iterable<string, array<mixed>>
+     */
+    public function providerForDefaultValue(): iterable
+    {
+        yield 'intersection' => [['en_GB', 'en'], ['en', 'de', 'el', 'en_US'], 'en'];
+        yield 'no available locale' => [['en_GB', 'en'], ['de', 'el', 'en_US'], ''];
+        yield 'user preferred language priority' => [['en_GB', 'en', 'de'], ['de', 'en', 'el'], 'en'];
+    }
+}