[Easy Unlock] Port the BluetoothConnection class to native code.

components/proximity_auth/bluetooth_connection_unittest.cc

Index: components/proximity_auth/bluetooth_connection_unittest.cc
diff --git a/components/proximity_auth/bluetooth_connection_unittest.cc b/components/proximity_auth/bluetooth_connection_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a4dea4d880fbf588a8de7119f923c34edd7494eb
--- /dev/null
+++ b/components/proximity_auth/bluetooth_connection_unittest.cc
@@ -0,0 +1,487 @@
+// Copyright 2014 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 "components/proximity_auth/bluetooth_connection.h"
+
+#include "base/message_loop/message_loop.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/run_loop.h"
+#include "components/proximity_auth/remote_device.h"
+#include "components/proximity_auth/wire_message.h"
+#include "device/bluetooth/bluetooth_adapter_factory.h"
+#include "device/bluetooth/bluetooth_uuid.h"
+#include "device/bluetooth/test/mock_bluetooth_adapter.h"
+#include "device/bluetooth/test/mock_bluetooth_device.h"
+#include "device/bluetooth/test/mock_bluetooth_socket.h"
+#include "net/base/io_buffer.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using testing::_;
+using testing::NiceMock;
+using testing::Ref;
+using testing::Return;
+using testing::SaveArg;
+using testing::StrictMock;
+
+namespace proximity_auth {
+namespace {
+
+const char kDeviceName[] = "Device name";
+const char kOtherDeviceName[] = "Other device name";
+
+const char kBluetoothAddress[] = "11:22:33:44:55:66";
+const char kOtherBluetoothAddress[] = "AA:BB:CC:DD:EE:FF";
+
+const char kSerializedMessage[] = "Yarrr, this be a serialized message. Yarr!";
+const int kSerializedMessageLength = strlen(kSerializedMessage);
+
+const char kUuid[] = "DEADBEEF-CAFE-FEED-FOOD-D15EA5EBEEF";
+
+const RemoteDevice kRemoteDevice = {kDeviceName, kBluetoothAddress};
+
+const int kReceiveBufferSize = 6;
+const char kReceiveBufferContents[] = "bytes";
+
+// Create a buffer for testing received data.
+scoped_refptr<net::IOBuffer> CreateReceiveBuffer() {
+  scoped_refptr<net::IOBuffer> buffer = new net::IOBuffer(kReceiveBufferSize);
+  memcpy(buffer->data(), kReceiveBufferContents, kReceiveBufferSize);
+  return buffer;
+}
+
+class MockBluetoothConnection : public BluetoothConnection {
+ public:
+  MockBluetoothConnection()
+      : BluetoothConnection(kRemoteDevice, device::BluetoothUUID(kUuid)) {}
+
+  // Bluetooth dependencies.
+  typedef device::BluetoothDevice::ConnectToServiceCallback
+      ConnectToServiceCallback;
+  typedef device::BluetoothDevice::ConnectToServiceErrorCallback
+      ConnectToServiceErrorCallback;
+  MOCK_METHOD4(ConnectToService,
+               void(device::BluetoothDevice* device,
+                    const device::BluetoothUUID& uuid,
+                    const ConnectToServiceCallback& callback,
+                    const ConnectToServiceErrorCallback& error_callback));
+
+  // Calls back into the parent Connection class.
+  MOCK_METHOD1(SetStatusProxy, void(Status status));
+  MOCK_METHOD1(OnBytesReceived, void(const std::string& bytes));
+  MOCK_METHOD2(OnDidSendMessage,
+               void(const WireMessage& message, bool success));
+
+  virtual void SetStatus(Status status) OVERRIDE {
+    SetStatusProxy(status);
+    BluetoothConnection::SetStatus(status);
+  }
+
+  using BluetoothConnection::Connect;
+  using BluetoothConnection::DeviceRemoved;
+  using BluetoothConnection::Disconnect;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MockBluetoothConnection);
+};
+
+class TestWireMessage : public WireMessage {
+ public:
+  TestWireMessage() : WireMessage("permit id", "payload") {}
+  virtual ~TestWireMessage() {}
+
+  virtual std::string Serialize() const OVERRIDE { return kSerializedMessage; }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestWireMessage);
+};
+
+}  // namespace
+
+class ProximityAuthBluetoothConnectionTest : public testing::Test {
+ public:
+  ProximityAuthBluetoothConnectionTest()
+      : adapter_(new StrictMock<device::MockBluetoothAdapter>),
+        device_(adapter_.get(), 0, kDeviceName, kBluetoothAddress, true, true),
+        socket_(new StrictMock<device::MockBluetoothSocket>),
+        uuid_(kUuid) {
+    device::BluetoothAdapterFactory::SetAdapterForTesting(adapter_);
+  }
+
+  // Transition the connection into an in-progress state.
+  void BeginConnecting(MockBluetoothConnection* connection) {

[Tim Song, 2014/09/22 23:30:38]

check STATUS == DISCONNECTED

[Ilya Sherman, 2014/09/23 05:24:22]

Done.

+    EXPECT_CALL(*connection, SetStatusProxy(Connection::IN_PROGRESS));
+    EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));

[Tim Song, 2014/09/22 23:30:39]

use ON_CALL instead.

[Ilya Sherman, 2014/09/23 05:24:22]

Done.

+    EXPECT_CALL(*adapter_, AddObserver(connection));
+    EXPECT_CALL(*connection, ConnectToService(&device_, uuid_, _, _));
+    connection->Connect();

[Tim Song, 2014/09/22 23:30:38]

check status == CONNECTING

[Ilya Sherman, 2014/09/23 05:24:22]

Done.

+  }
+
+  // Transition the connection into a connected state.
+  void Connect(MockBluetoothConnection* connection) {
+    device::BluetoothDevice::ConnectToServiceCallback callback;
+    EXPECT_CALL(*connection, SetStatusProxy(Connection::IN_PROGRESS));
+    EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));

[Tim Song, 2014/09/22 23:30:39]

use ON_CALL

[Ilya Sherman, 2014/09/23 05:24:22]

Done.

+    EXPECT_CALL(*adapter_, AddObserver(connection));
+    EXPECT_CALL(*connection, ConnectToService(_, _, _, _))
+        .WillOnce(SaveArg<2>(&callback));
+    connection->Connect();
+    ASSERT_FALSE(callback.is_null());
+
+    EXPECT_CALL(*connection, SetStatusProxy(Connection::CONNECTED));
+    EXPECT_CALL(*socket_, Receive(_, _, _));
+    callback.Run(socket_);

[Tim Song, 2014/09/22 23:30:39]

Check status == CONNECTED

[Ilya Sherman, 2014/09/23 05:24:22]

Done.

+  }
+
+ protected:
+  // Mocks used for verifying interactions with the Bluetooth subsystem.
+  scoped_refptr<StrictMock<device::MockBluetoothAdapter> > adapter_;
+  NiceMock<device::MockBluetoothDevice> device_;
+  scoped_refptr<StrictMock<device::MockBluetoothSocket> > socket_;
+
+  device::BluetoothUUID uuid_;
+
+ private:
+  base::MessageLoop message_loop_;
+};
+
+TEST_F(ProximityAuthBluetoothConnectionTest, Connect_ConnectionWasInProgress) {
+  // Create an in-progress connection.
+  StrictMock<MockBluetoothConnection> connection;
+  BeginConnecting(&connection);
+
+  // A second call to Connect() should be ignored.
+  EXPECT_CALL(connection, SetStatusProxy(_)).Times(0);
+  connection.Connect();
+
+  // The connection cleans up after itself upon destruction.
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, Connect_ConnectionWasConnected) {
+  // Create a connected connection.
+  StrictMock<MockBluetoothConnection> connection;
+  Connect(&connection);
+
+  // A second call to Connect() should be ignored.
+  EXPECT_CALL(connection, SetStatusProxy(_)).Times(0);
+  connection.Connect();
+
+  // The connection disconnects and unregisters as an observer upon destruction.
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, Connect_NoBluetoothAdapter) {
+  // Some platforms do not support Bluetooth. This test is only meaningful on
+  // those platforms.
+  adapter_ = NULL;
+  if (device::BluetoothAdapterFactory::IsBluetoothAdapterAvailable())
+    return;
+
+  StrictMock<MockBluetoothConnection> connection;
+  EXPECT_CALL(connection, SetStatusProxy(_)).Times(0);
+  connection.Connect();
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, Connect_DeviceMissing) {
+  StrictMock<MockBluetoothConnection> connection;
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_))
+      .WillOnce(Return(static_cast<device::BluetoothDevice*>(NULL)));
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  connection.Connect();
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Connect_DeviceRemovedWhileConnecting) {
+  // Create an in-progress connection.
+  StrictMock<MockBluetoothConnection> connection;
+  BeginConnecting(&connection);
+
+  // Remove the device while the connection is in-progress. This should cause
+  // the connection to disconnect.
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  connection.DeviceRemoved(adapter_.get(), &device_);
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Connect_OtherDeviceRemovedWhileConnecting) {
+  // Create an in-progress connection.
+  StrictMock<MockBluetoothConnection> connection;
+  BeginConnecting(&connection);
+
+  // Remove a device other than the one that is being connected to. This should
+  // not have any effect on the connection.
+  NiceMock<device::MockBluetoothDevice> other_device(
+      adapter_.get(), 0, kOtherDeviceName, kOtherBluetoothAddress, true, true);
+  EXPECT_CALL(connection, SetStatusProxy(_)).Times(0);
+  connection.DeviceRemoved(adapter_.get(), &other_device);
+
+  // The connection removes itself as an observer when it is destroyed.
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, Connect_ConnectionFails) {
+  StrictMock<MockBluetoothConnection> connection;
+
+  device::BluetoothDevice::ConnectToServiceErrorCallback error_callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));
+  EXPECT_CALL(*adapter_, AddObserver(&connection));
+  EXPECT_CALL(connection, ConnectToService(&device_, uuid_, _, _))
+      .WillOnce(SaveArg<3>(&error_callback));
+  connection.Connect();
+  ASSERT_FALSE(error_callback.is_null());
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  error_callback.Run("super descriptive error message");
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, Connect_ConnectionSucceeds) {
+  StrictMock<MockBluetoothConnection> connection;
+
+  device::BluetoothDevice::ConnectToServiceCallback callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));
+  EXPECT_CALL(*adapter_, AddObserver(&connection));
+  EXPECT_CALL(connection, ConnectToService(&device_, uuid_, _, _))
+      .WillOnce(SaveArg<2>(&callback));
+  connection.Connect();

[Tim Song, 2014/09/22 23:30:38]

Why not just use the ProximityAuthBluetoothConnectionTest::Connect() utility
function? There's a few more places below as well.

[Ilya Sherman, 2014/09/23 05:24:22]

Because we need to save a reference to the callback, which the Connect()
function doesn't do.  I tried to use the Connect() function everywhere that
wasn't specifically testing details of the connection process.

[Tim Song, 2014/09/23 21:22:12]

I don't understand. This function is almost line-by-line the same as Connect().
Also, if you need the callback, why not have Connect return it?

[Ilya Sherman, 2014/09/23 22:07:07]

Hmm, I suppose you're right.  Okay, I've updated this test as well as the three
below to use the Connect() utility function.  Note that I ended up adding an
additional, more complex, utility function for connecting and saving callbacks. 
Let me know if you think that's worth it, or if it's overly complex.

+  ASSERT_FALSE(callback.is_null());
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::CONNECTED));
+  EXPECT_CALL(*socket_, Receive(_, _, _));
+  callback.Run(socket_);
+
+  // The connection disconnects and unregisters as an observer upon destruction.
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Connect_ConnectionSucceeds_ThenDeviceRemoved) {
+  StrictMock<MockBluetoothConnection> connection;
+
+  device::BluetoothDevice::ConnectToServiceCallback callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));
+  EXPECT_CALL(*adapter_, AddObserver(&connection));
+  EXPECT_CALL(connection, ConnectToService(&device_, uuid_, _, _))
+      .WillOnce(SaveArg<2>(&callback));
+  connection.Connect();
+  ASSERT_FALSE(callback.is_null());
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::CONNECTED));
+  EXPECT_CALL(*socket_, Receive(_, _, _));
+  callback.Run(socket_);
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  connection.DeviceRemoved(adapter_.get(), &device_);
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Connect_ConnectionSucceeds_ReceiveData) {
+  StrictMock<MockBluetoothConnection> connection;
+
+  // Connect.
+  device::BluetoothDevice::ConnectToServiceCallback callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));
+  EXPECT_CALL(*adapter_, AddObserver(&connection));
+  EXPECT_CALL(connection, ConnectToService(&device_, uuid_, _, _))
+      .WillOnce(SaveArg<2>(&callback));
+  connection.Connect();
+  ASSERT_FALSE(callback.is_null());
+
+  device::BluetoothSocket::ReceiveCompletionCallback receive_callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::CONNECTED));
+  EXPECT_CALL(*socket_, Receive(_, _, _))
+      .WillOnce(SaveArg<1>(&receive_callback));
+  callback.Run(socket_);
+  ASSERT_FALSE(receive_callback.is_null());
+
+  // Receive some data. Once complete, the connection should re-register to be
+  // ready receive more data.
+  scoped_refptr<net::IOBuffer> buffer = CreateReceiveBuffer();
+  EXPECT_CALL(
+      connection,
+      OnBytesReceived(std::string(kReceiveBufferContents, kReceiveBufferSize)));
+  EXPECT_CALL(*socket_, Receive(_, _, _));
+  receive_callback.Run(kReceiveBufferSize, buffer);
+  base::RunLoop run_loop;
+  run_loop.RunUntilIdle();
+
+  // The connection disconnects and unregisters as an observer upon destruction.
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Connect_ConnectionSucceeds_ReceiveDataAfterReceiveError) {
+  StrictMock<MockBluetoothConnection> connection;
+
+  // Connect.
+  device::BluetoothDevice::ConnectToServiceCallback callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));
+  EXPECT_CALL(*adapter_, AddObserver(&connection));
+  EXPECT_CALL(connection, ConnectToService(&device_, uuid_, _, _))
+      .WillOnce(SaveArg<2>(&callback));
+  connection.Connect();
+  ASSERT_FALSE(callback.is_null());
+
+  device::BluetoothSocket::ReceiveErrorCompletionCallback
+      receive_error_callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::CONNECTED));
+  EXPECT_CALL(*socket_, Receive(_, _, _))
+      .WillOnce(SaveArg<2>(&receive_error_callback));
+  callback.Run(socket_);
+  ASSERT_FALSE(receive_error_callback.is_null());
+
+  // Simulate an error while receiving data. The connection should re-register
+  // to be ready receive more data despite the error.
+  device::BluetoothSocket::ReceiveCompletionCallback receive_callback;
+  EXPECT_CALL(*socket_, Receive(_, _, _))
+      .WillOnce(SaveArg<1>(&receive_callback));
+  receive_error_callback.Run(device::BluetoothSocket::kSystemError,
+                             "The system is down. They're taking over!");
+  base::RunLoop run_loop;
+  run_loop.RunUntilIdle();
+
+  // Receive some data.
+  scoped_refptr<net::IOBuffer> buffer = CreateReceiveBuffer();
+  EXPECT_CALL(
+      connection,
+      OnBytesReceived(std::string(kReceiveBufferContents, kReceiveBufferSize)));
+  EXPECT_CALL(*socket_, Receive(_, _, _));
+  receive_callback.Run(kReceiveBufferSize, buffer);
+  base::RunLoop run_loop2;
+  run_loop2.RunUntilIdle();
+
+  // The connection disconnects and unregisters as an observer upon destruction.
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Disconnect_ConnectionWasAlreadyDisconnected) {
+  StrictMock<MockBluetoothConnection> connection;
+  EXPECT_CALL(connection, SetStatusProxy(_)).Times(0);
+  connection.Disconnect();
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Disconnect_ConnectionWasInProgress) {
+  // Create an in-progress connection.
+  StrictMock<MockBluetoothConnection> connection;
+  BeginConnecting(&connection);
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  connection.Disconnect();
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Disconnect_ConnectionWasConnected) {
+  // Create a connected connection.
+  StrictMock<MockBluetoothConnection> connection;
+  Connect(&connection);
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  connection.Disconnect();
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       Connect_ThenDisconnectWhileInProgress_ThenBackingConnectionSucceeds) {
+  StrictMock<MockBluetoothConnection> connection;
+  device::BluetoothDevice::ConnectToServiceCallback callback;
+  EXPECT_CALL(connection, SetStatusProxy(Connection::IN_PROGRESS));
+  EXPECT_CALL(*adapter_, GetDevice(_)).WillOnce(Return(&device_));
+  EXPECT_CALL(*adapter_, AddObserver(&connection));
+  EXPECT_CALL(connection, ConnectToService(&device_, uuid_, _, _))
+      .WillOnce(SaveArg<2>(&callback));
+  connection.Connect();

[Tim Song, 2014/09/22 23:30:38]

Why not use BeginConnection?

[Ilya Sherman, 2014/09/23 05:24:22]

Same as before: We need to save a reference to the callback.

+  ASSERT_FALSE(callback.is_null());
+
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  connection.Disconnect();
+
+  EXPECT_CALL(connection, SetStatusProxy(_)).Times(0);
+  EXPECT_CALL(*socket_, Receive(_, _, _)).Times(0);
+  callback.Run(socket_);
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest,
+       SendMessage_SendsExpectedDataOverTheWire) {
+  // Create a connected connection.
+  StrictMock<MockBluetoothConnection> connection;
+  Connect(&connection);
+
+  scoped_refptr<net::IOBuffer> buffer;
+  scoped_ptr<TestWireMessage> wire_message(new TestWireMessage);
+  EXPECT_CALL(*socket_, Send(_, kSerializedMessageLength, _, _))
+      .WillOnce(SaveArg<0>(&buffer));
+  connection.SendMessage(wire_message.PassAs<WireMessage>());
+  ASSERT_TRUE(buffer.get());
+  EXPECT_EQ(kSerializedMessage,
+            std::string(buffer->data(), kSerializedMessageLength));
+
+  // The connection disconnects and unregisters as an observer upon destruction.
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, SendMessage_Success) {
+  // Create a connected connection.
+  StrictMock<MockBluetoothConnection> connection;
+  Connect(&connection);
+
+  scoped_ptr<TestWireMessage> wire_message(new TestWireMessage);
+  // Ownership will be transfered below, so grab a reference here.
+  TestWireMessage* expected_wire_message = wire_message.get();
+
+  device::BluetoothSocket::SendCompletionCallback callback;
+  EXPECT_CALL(*socket_, Send(_, _, _, _)).WillOnce(SaveArg<2>(&callback));
+  connection.SendMessage(wire_message.PassAs<WireMessage>());
+  ASSERT_FALSE(callback.is_null());
+
+  EXPECT_CALL(connection, OnDidSendMessage(Ref(*expected_wire_message), true));
+  callback.Run(kSerializedMessageLength);
+
+  // The connection disconnects and unregisters as an observer upon destruction.
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+}
+
+TEST_F(ProximityAuthBluetoothConnectionTest, SendMessage_Failure) {
+  // Create a connected connection.
+  StrictMock<MockBluetoothConnection> connection;
+  Connect(&connection);
+
+  scoped_ptr<TestWireMessage> wire_message(new TestWireMessage);
+  // Ownership will be transfered below, so grab a reference here.
+  TestWireMessage* expected_wire_message = wire_message.get();
+
+  device::BluetoothSocket::ErrorCompletionCallback error_callback;
+  EXPECT_CALL(*socket_, Send(_, _, _, _)).WillOnce(SaveArg<3>(&error_callback));
+  connection.SendMessage(wire_message.PassAs<WireMessage>());
+
+  ASSERT_FALSE(error_callback.is_null());
+  EXPECT_CALL(connection, OnDidSendMessage(Ref(*expected_wire_message), false));
+  EXPECT_CALL(connection, SetStatusProxy(Connection::DISCONNECTED));
+  EXPECT_CALL(*socket_, Disconnect(_));
+  EXPECT_CALL(*adapter_, RemoveObserver(&connection));
+  error_callback.Run("The most helpful of error messages");
+}
+
+}  // namespace proximity_auth