Issue #2098697 by tstoeckler, sxnc, Gábor Hojtsy: Provide a LocaleConfigManager::hasTranslation().

core/modules/locale/lib/Drupal/locale/LocaleConfigManager.php

@@ -279,6 +279,23 @@ public function translateString($name, $langcode, $source, $context) {
     return FALSE;
   }
 
+  /**
+   * Checks whether a language has configuration translation.
+   *
+   * @param string $name
+   *   Configuration name.
+   * @param \Drupal\Core\Language\Language $language
+   *   A language object.
+   *
+   * @return bool
+   *   A boolean indicating if a language has configuration translations.
+   */
+  public function hasTranslation($name, Language $language) {
+    $locale_name = static::localeConfigName($language->id, $name);
+    $translation = $this->configStorage->read($locale_name);
+    return !empty($translation);
+  }
+
   /**
    * Provides configuration data location for given langcode and name.
    *
@@ -293,4 +310,5 @@ public function translateString($name, $langcode, $source, $context) {
   public static function localeConfigName($langcode, $name = NULL) {
     return rtrim('locale.config.' . $langcode . '.' . $name, '.');
   }
+
 }

core/modules/locale/lib/Drupal/locale/Tests/LocaleConfigManagerTest.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\locale\Tests\LocaleConfigManagerTest.
+ */
+
+namespace Drupal\locale\Tests;
+
+use Drupal\locale\LocaleConfigManager;
+use Drupal\Core\Language\Language;
+use Drupal\Core\Config\StorageException;
+use Drupal\simpletest\DrupalUnitTestBase;
+
+/**
+ * Provides tests for \Drupal\locale\LocaleConfigManager
+ */
+class LocaleConfigManagerTest extends DrupalUnitTestBase {
+
+  /**
+   * A list of modules to install for this test.
+   *
+   * @var array
+   */
+  public static $modules = array('locale', 'locale_test');
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getInfo() {
+    return array(
+      'name' => 'Locale config manager',
+      'description' => 'Tests that the locale config manager operates correctly.',
+      'group' => 'Locale',
+    );
+  }
+
+  /**
+   * Tests hasTranslation().
+   */
+  public function testHasTranslation() {
+    $locale_config_manager = new LocaleConfigManager(
+      // In contrast to the actual configuration we use the installer storage
+      // as the config storage. That way, we do not actually have to install
+      // the module and can extend DrupalUnitTestBase.
+      $this->container->get('config.storage.installer'),
+      $this->container->get('config.storage.schema'),
+      $this->container->get('config.storage.installer'),
+      $this->container->get('locale.storage')
+    );
+
+    $language = new Language(array('id' => 'de'));
+    // The installer storage throws an expcetion when requesting a non-existing
+    // file.
+    try {
+      $locale_config_manager->hasTranslation('locale_test.no_translation', $language);
+    }
+    catch (StorageException $exception) {
+      $result = FALSE;
+    }
+    $this->assertIdentical(FALSE, $result);
+
+    $result = $locale_config_manager->hasTranslation('locale_test.translation', $language);
+    $this->assertIdentical(TRUE, $result);
+  }
+}

core/modules/locale/tests/modules/locale_test/config/locale.config.de.locale_test.translation.yml

+test: German test

core/modules/locale/tests/modules/locale_test/config/locale_test.no_translation.yml

+test: Test

core/modules/locale/tests/modules/locale_test/config/locale_test.translation.yml

+test: English test