Added missing unit test for translate_service.cc

Added missing unit test for translate_service.cc

Bug: 727459
Change-Id: Iae3cdded7bb934fd59a7248cf342bce85c44ee69
Reviewed-on: https://chromium-review.googlesource.com/564871Reviewed-by: David Vallet <dvallet@chromium.org>
Commit-Queue: Jon Napper <napper@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485507}

chrome/browser/translate/translate_service_unittest.cc

@@ -5,6 +5,9 @@
 #include "chrome/browser/translate/translate_service.h"
 
 #include "build/build_config.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/testing_pref_service.h"
+#include "components/translate/core/browser/translate_download_manager.h"
 #include "content/public/common/url_constants.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
@@ -14,6 +17,7 @@
 #include "extensions/common/constants.h"
 #endif
 
+// Test the check that determines if a URL should be translated.
 TEST(TranslateServiceTest, CheckTranslatableURL) {
   GURL empty_url = GURL(std::string());
   EXPECT_FALSE(TranslateService::IsTranslatableURL(empty_url));
@@ -41,3 +45,40 @@ TEST(TranslateServiceTest, CheckTranslatableURL) {
   GURL right_url = GURL("http://www.tamurayukari.com/");
   EXPECT_TRUE(TranslateService::IsTranslatableURL(right_url));
 }
+
+// Test selection of translation target language.
+TEST(TranslateServiceTest, GetTargetLanguage) {
+  TranslateService::InitializeForTesting();
+
+  translate::TranslateDownloadManager* const download_manager =
+      translate::TranslateDownloadManager::GetInstance();
+  download_manager->ResetForTesting();
+
+#if defined(OS_CHROMEOS)
+  const char kLanguagePrefName[] = "settings.language.preferred_languages";
+#else
+  const char kLanguagePrefName[] = "intl.accept_languages";
+#endif
+  // Setup the accept / preferred languages preferences.
+  TestingPrefServiceSimple prefs;
+  prefs.registry()->RegisterStringPref(kLanguagePrefName, std::string());
+  prefs.SetString(kLanguagePrefName, "fr");
+
+  // Test valid application locale.
+  download_manager->set_application_locale("en");
+  EXPECT_EQ("en", TranslateService::GetTargetLanguage(&prefs));
+
+  download_manager->set_application_locale("es");
+  EXPECT_EQ("es", TranslateService::GetTargetLanguage(&prefs));
+
+  // No valid application locale, so fall back to accept language.
+  download_manager->set_application_locale("");
+  EXPECT_EQ("fr", TranslateService::GetTargetLanguage(&prefs));
+
+  // Ensure unsupported language is ignored.
+  prefs.SetString(kLanguagePrefName, "xx,fr");
+  EXPECT_EQ("fr", TranslateService::GetTargetLanguage(&prefs));
+
+  download_manager->ResetForTesting();
+  TranslateService::ShutdownForTesting();
+}