Create a FakeTetherService, which stubs out TetherService for development.

chrome/browser/chromeos/tether/tether_service.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_TETHER_TETHER_SERVICE_H_
 #define CHROME_BROWSER_CHROMEOS_TETHER_TETHER_SERVICE_H_
 
 #include <memory>
 
+#include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "chromeos/dbus/session_manager_client.h"
 #include "chromeos/network/network_state_handler.h"
 #include "chromeos/network/network_state_handler_observer.h"
 #include "components/cryptauth/cryptauth_device_manager.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/prefs/pref_change_registrar.h"
 #include "device/bluetooth/bluetooth_adapter.h"
@@ skipping 17 matching lines @@
                 chromeos::SessionManagerClient* session_manager_client,
                 cryptauth::CryptAuthService* cryptauth_service,
                 chromeos::NetworkStateHandler* network_state_handler);
   ~TetherService() override;
 
   // Gets TetherService instance.
   static TetherService* Get(Profile* profile);
 
   static void RegisterProfilePrefs(PrefRegistrySimple* registry);
 
+  // Whether the Tether feature has been enabled via a chrome://about or
+  // command line flag.
+  static bool IsFeatureFlagEnabled();
+
   // Attempt to start the Tether module. Only succeeds if all conditions to
   // reach chromeos::NetworkStateHandler::TechnologyState::ENABLED are reached.
   // Should only be called once a user is logged in.
-  void StartTetherIfEnabled();
+  virtual void StartTetherIfEnabled();
 
   // Stop the Tether module.
-  void StopTether();
+  virtual void StopTether();
 
  protected:
   // KeyedService:
   void Shutdown() override;
 
   // chromeos::PowerManagerClient::Observer:
   void SuspendImminent() override;
   void SuspendDone(const base::TimeDelta& sleep_duration) override;
 
   // chromeos::SessionManagerClient::Observer:
   void ScreenIsLocked() override;
   void ScreenIsUnlocked() override;
 
   // cryptauth::CryptAuthDeviceManager::Observer
   void OnSyncFinished(cryptauth::CryptAuthDeviceManager::SyncResult sync_result,
                       cryptauth::CryptAuthDeviceManager::DeviceChangeResult
                           device_change_result) override;
 
   // device::BluetoothAdapter::Observer:
   void AdapterPoweredChanged(device::BluetoothAdapter* adapter,
                              bool powered) override;
 
   // chromeos::NetworkStateHandlerObserver:
   void DeviceListChanged() override;
 
   // Callback when the controlling pref changes.
   void OnPrefsChanged();
 
+  // Whether Tether hosts are available.
+  virtual bool HasSyncedTetherHosts() const;
+
   virtual void UpdateTetherTechnologyState();
+  chromeos::NetworkStateHandler::TechnologyState GetTetherTechnologyState();
+
+  chromeos::NetworkStateHandler* network_state_handler() {
+    return network_state_handler_;
+  }
 
  private:
   friend class TetherServiceTest;
-
-  chromeos::NetworkStateHandler::TechnologyState GetTetherTechnologyState();
+  FRIEND_TEST_ALL_PREFIXES(TetherServiceTest, TestFeatureFlagEnabled);
 
   void OnBluetoothAdapterFetched(
       scoped_refptr<device::BluetoothAdapter> adapter);
 
   bool IsBluetoothAvailable() const;
 
-  // Whether Tether hosts are available.
-  bool HasSyncedTetherHosts() const;
-
-  // Whether the Tether feature has been enabled via an about or command line
-  // flag.
-  bool IsFeatureFlagEnabled() const;
-
   // Whether Tether is allowed to be used. If the controlling preference
   // is set (from policy), this returns the preference value. Otherwise, it is
   // permitted if the flag is enabled.
   bool IsAllowedByPolicy() const;
 
   // Whether Tether is enabled.
   bool IsEnabledbyPreference() const;
 
   // Whether the service has been shut down.
   bool shut_down_ = false;
@@ skipping 10 matching lines @@
 
   PrefChangeRegistrar registrar_;
   scoped_refptr<device::BluetoothAdapter> adapter_;
 
   base::WeakPtrFactory<TetherService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TetherService);
 };
 
 #endif  // CHROME_BROWSER_CHROMEOS_TETHER_TETHER_SERVICE_H_