bluetooth: mac: write characteristic implementation

device/bluetooth/test/mock_bluetooth_cbcharacteristic_mac.h

 // Copyright 2016 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 DEVICE_BLUETOOTH_TEST_MOCK_BLUETOOTH_CBCHARACTERISTIC_MAC_H_
 #define DEVICE_BLUETOOTH_TEST_MOCK_BLUETOOTH_CBCHARACTERISTIC_MAC_H_
 
 #include "base/mac/sdk_forward_declarations.h"
 #include "build/build_config.h"
 
 #import <CoreBluetooth/CoreBluetooth.h>
 
 // This class mocks the behavior of a CBCharacteristic.
 @interface MockCBCharacteristic : NSObject
 
 @property(readonly, nonatomic) CBUUID* UUID;
 @property(readonly, nonatomic) CBCharacteristic* characteristic;
 
 - (instancetype)initWithService:(CBService*)service
                          CBUUID:(CBUUID*)uuid
                      properties:(int)properties;
 
 // Methods for faking events.
 - (void)simulateReadWithValue:(NSData*)value error:(NSError*)error;
+- (void)simulateWriteWithError:(NSError*)error;
 
 @end
 
 #endif  // DEVICE_BLUETOOTH_TEST_MOCK_BLUETOOTH_CBCHARACTERISTIC_MAC_H_