Bluetooth: macOS: Implementing read/write for descriptors

device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.mm

 // 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.
 
 #include "device/bluetooth/test/mock_bluetooth_cbdescriptor_mac.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
 #include "device/bluetooth/bluetooth_gatt_characteristic.h"
 
 using base::mac::ObjCCast;
 using base::scoped_nsobject;
 
 @interface MockCBDescriptor () {
   // Owner of this instance.
   CBCharacteristic* _characteristic;
   scoped_nsobject<CBUUID> _UUID;
+  scoped_nsobject<NSData> _value;
 }
 @end
 
 @implementation MockCBDescriptor
 
 - (instancetype)initWithCharacteristic:(CBCharacteristic*)characteristic
                                 CBUUID:(CBUUID*)uuid {
   self = [super init];
   if (self) {
     _characteristic = characteristic;
@@ skipping 15 matching lines @@
       [aClass isSubclassOfClass:[CBDescriptor class]]) {
     return YES;
   }
   return [super isKindOfClass:aClass];
 }
 
 - (CBUUID*)UUID {
   return _UUID.get();
 }
 
+- (NSData*)value {
+  return _value.get();
+}
+
 - (CBDescriptor*)descriptor {
   return ObjCCast<CBDescriptor>(self);
 }
 
 - (CBCharacteristic*)characteristic {
   return _characteristic;
 }
 
+- (void)simulateReadWithValue:(id)value error:(NSError*)error {
+  _value.reset([value copy]);
+  CBPeripheral* peripheral = _characteristic.service.peripheral;
+  [peripheral.delegate peripheral:peripheral
+      didUpdateValueForDescriptor:self.descriptor
+                            error:error];
+}
+
+- (void)simulateWriteWithError:(NSError*)error {
+  CBPeripheral* peripheral = _characteristic.service.peripheral;
+  [peripheral.delegate peripheral:peripheral
+       didWriteValueForDescriptor:self.descriptor
+                            error:error];
+}
+
 @end