[IOS][Language] Language Settings - LanguageSettingsMediator unittests

- Adds unittests for the LanguageSettingsMediator.
- Uses a PrefObserverBridge instead of a BooleanObserver to observe
  prefs::kOfferTranslateEnabled as it's more straight forward to stop
  during the shutdown and more consistent with the other observed prefs.
- Adds a method to the data source to stop observing the model which is
  called during the test teardown as well as by the TableViewController
  when being shutdown.

Bug: 957688
Change-Id: I003df740b56d611717c85193e0d61b592f1f90d5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1642812Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#666153}

ios/chrome/browser/ui/settings/language/BUILD.gn

@@ -55,3 +55,27 @@ source_set("language_ui") {
     "//ui/base",
   ]
 }
+
+source_set("unit_tests") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+  testonly = true
+  sources = [
+    "language_settings_mediator_unittest.mm",
+  ]
+  deps = [
+    "//base/test:test_support",
+    "//components/language/core/browser",
+    "//components/pref_registry",
+    "//components/prefs",
+    "//components/sync_preferences",
+    "//components/sync_preferences:test_support",
+    "//components/translate/core/browser",
+    "//ios/chrome/browser/browser_state:test_support",
+    "//ios/chrome/browser/prefs:browser_prefs",
+    "//ios/chrome/browser/translate",
+    "//ios/chrome/browser/ui/settings/language",
+    "//ios/chrome/browser/ui/settings/language:language_ui",
+    "//ios/chrome/browser/ui/settings/language/cells",
+    "//testing/gtest",
+  ]
+}

ios/chrome/browser/ui/settings/language/language_settings_data_source.h

@@ -25,6 +25,9 @@
 // Returns whether or not Translate is enabled.
 - (BOOL)translateEnabled;
 
+// Stops observing the model. This is required during the shutdown.
+- (void)stopObservingModel;
+
 // The consumer for this protocol.
 @property(nonatomic, weak) id<LanguageSettingsConsumer> consumer;
 

ios/chrome/browser/ui/settings/language/language_settings_mediator.mm

@@ -26,8 +26,6 @@
 #import "ios/chrome/browser/ui/settings/language/cells/language_item.h"
 #import "ios/chrome/browser/ui/settings/language/language_settings_consumer.h"
 #import "ios/chrome/browser/ui/settings/language/language_settings_histograms.h"
-#import "ios/chrome/browser/ui/settings/utils/observable_boolean.h"
-#import "ios/chrome/browser/ui/settings/utils/pref_backed_boolean.h"
 #include "ios/chrome/grit/ios_strings.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
@@ -35,10 +33,13 @@
 #error "This file requires ARC support."
 #endif
 
-@interface LanguageSettingsMediator () <BooleanObserver, PrefObserverDelegate> {
+@interface LanguageSettingsMediator () <PrefObserverDelegate> {
   // Registrar for pref change notifications.
   std::unique_ptr<PrefChangeRegistrar> _prefChangeRegistrar;
 
+  // Pref observer to track changes to prefs::kOfferTranslateEnabled.
+  std::unique_ptr<PrefObserverBridge> _offerTranslatePrefObserverBridge;
+
   // Pref observer to track changes to language::prefs::kAcceptLanguages.
   std::unique_ptr<PrefObserverBridge> _acceptLanguagesPrefObserverBridge;
 
@@ -52,9 +53,6 @@
 // The BrowserState passed to this instance.
 @property(nonatomic, assign) ios::ChromeBrowserState* browserState;
 
-// An observable boolean backed by prefs::kOfferTranslateEnabled.
-@property(nonatomic, strong) PrefBackedBoolean* translateEnabledPref;
-
 @end
 
 @implementation LanguageSettingsMediator
@@ -67,13 +65,12 @@
   if (self) {
     _browserState = browserState;
 
-    _translateEnabledPref = [[PrefBackedBoolean alloc]
-        initWithPrefService:browserState->GetPrefs()
-                   prefName:prefs::kOfferTranslateEnabled];
-    [_translateEnabledPref setObserver:self];
-
     _prefChangeRegistrar = std::make_unique<PrefChangeRegistrar>();
     _prefChangeRegistrar->Init(browserState->GetPrefs());
+    _offerTranslatePrefObserverBridge =
+        std::make_unique<PrefObserverBridge>(self);
+    _offerTranslatePrefObserverBridge->ObserveChangesForPreference(
+        prefs::kOfferTranslateEnabled, _prefChangeRegistrar.get());
     _acceptLanguagesPrefObserverBridge =
         std::make_unique<PrefObserverBridge>(self);
     _acceptLanguagesPrefObserverBridge->ObserveChangesForPreference(
@@ -89,26 +86,27 @@
   return self;
 }
 
-#pragma mark - BooleanObserver
-
-// Called when the value of prefs::kOfferTranslateEnabled changes.
-- (void)booleanDidChange:(id<ObservableBoolean>)observableBoolean {
-  DCHECK_EQ(self.translateEnabledPref, observableBoolean);
-
-  // Inform the consumer.
-  [self.consumer translateEnabled:observableBoolean.value];
+- (void)dealloc {
+  // In case this has not been explicitly called.
+  [self stopObservingModel];
 }
 
 #pragma mark - PrefObserverDelegate
 
-// Called when the value of language::prefs::kAcceptLanguages or
+// Called when the value of prefs::kOfferTranslateEnabled,
+// language::prefs::kAcceptLanguages or
 // language::prefs::kFluentLanguages change.
 - (void)onPreferenceChanged:(const std::string&)preferenceName {
-  DCHECK(preferenceName == language::prefs::kAcceptLanguages ||
+  DCHECK(preferenceName == prefs::kOfferTranslateEnabled ||
+         preferenceName == language::prefs::kAcceptLanguages ||
          preferenceName == language::prefs::kFluentLanguages);
 
-  // Inform the consumer
-  [self.consumer languagePrefsChanged];
+  // Inform the consumer.
+  if (preferenceName == prefs::kOfferTranslateEnabled) {
+    [self.consumer translateEnabled:[self translateEnabled]];
+  } else {
+    [self.consumer languagePrefsChanged];
+  }
 }
 
 #pragma mark - LanguageSettingsDataSource
@@ -205,13 +203,22 @@
 }
 
 - (BOOL)translateEnabled {
-  return self.translateEnabledPref.value;
+  return self.browserState->GetPrefs()->GetBoolean(
+      prefs::kOfferTranslateEnabled);
+}
+
+- (void)stopObservingModel {
+  _offerTranslatePrefObserverBridge.reset();
+  _acceptLanguagesPrefObserverBridge.reset();
+  _fluentLanguagesPrefObserverBridge.reset();
+  _prefChangeRegistrar.reset();
 }
 
 #pragma mark - LanguageSettingsCommands
 
 - (void)setTranslateEnabled:(BOOL)enabled {
-  [self.translateEnabledPref setValue:enabled];
+  self.browserState->GetPrefs()->SetBoolean(prefs::kOfferTranslateEnabled,
+                                            enabled);
 
   UMA_HISTOGRAM_ENUMERATION(
       kLanguageSettingsActionsHistogram,

ios/chrome/browser/ui/settings/language/language_settings_table_view_controller.h

@@ -6,6 +6,7 @@
 #define IOS_CHROME_BROWSER_UI_SETTINGS_LANGUAGE_LANGUAGE_SETTINGS_TABLE_VIEW_CONTROLLER_H_
 
 #import "ios/chrome/browser/ui/settings/language/language_settings_consumer.h"
+#import "ios/chrome/browser/ui/settings/settings_navigation_controller.h"
 #import "ios/chrome/browser/ui/settings/settings_root_table_view_controller.h"
 
 @protocol LanguageSettingsDataSource;
@@ -14,7 +15,8 @@
 // Controller for the UI that allows the user to change language settings such
 // as the ordered list of accept languages and their Translate preferences.
 @interface LanguageSettingsTableViewController
-    : SettingsRootTableViewController <LanguageSettingsConsumer>
+    : SettingsRootTableViewController <LanguageSettingsConsumer,
+                                       SettingsControllerProtocol>
 
 // The designated initializer. |dataSource| and |commandHandler| must not be
 // nil. |commandHandler| will not be retained.

ios/chrome/browser/ui/settings/language/language_settings_table_view_controller.mm

@@ -159,6 +159,12 @@ typedef NS_ENUM(NSInteger, ItemType) {
   [self setTranslateSwitchItemEnabled:!self.isEditing];
 }
 
+#pragma mark - SettingsControllerProtocol
+
+- (void)settingsWillBeDismissed {
+  [self.dataSource stopObservingModel];
+}
+
 #pragma mark - UITableViewDelegate
 
 - (UITableViewCellEditingStyle)tableView:(UITableView*)tableView

ios/chrome/test/BUILD.gn

@@ -238,6 +238,7 @@ test("ios_chrome_unittests") {
     "//ios/chrome/browser/ui/settings/autofill:unit_tests",
     "//ios/chrome/browser/ui/settings/cells:unit_tests",
     "//ios/chrome/browser/ui/settings/clear_browsing_data:unit_tests",
+    "//ios/chrome/browser/ui/settings/language:unit_tests",
     "//ios/chrome/browser/ui/settings/password:unit_tests",
     "//ios/chrome/browser/ui/settings/sync:unit_tests",
     "//ios/chrome/browser/ui/side_swipe:unit_tests",