fastboot/socket_test.cpp - android-core - Git at Google

 /*
  * Copyright (C) 2015 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 // Tests socket functionality using loopback connections. The UDP tests assume that no packets are
 // lost, which should be the case for loopback communication, but is not guaranteed.
 //
 // Also tests our SocketMock class to make sure it works as expected and reports errors properly
 // if the mock expectations aren't met during a test.

 #include "socket.h"
 #include "socket_mock.h"

 #include <list>

 #include <gtest/gtest-spi.h>
 #include <gtest/gtest.h>

 static constexpr int kShortTimeoutMs = 10;
 static constexpr int kTestTimeoutMs = 3000;

 // Creates connected sockets |server| and |client|. Returns true on success.
 bool MakeConnectedSockets(Socket::Protocol protocol, std::unique_ptr<Socket>* server,
                           std::unique_ptr<Socket>* client,
                           const std::string hostname = "localhost") {
     *server = Socket::NewServer(protocol, 0);
     if (*server == nullptr) {
         ADD_FAILURE() << "Failed to create server.";
         return false;
     }

     *client = Socket::NewClient(protocol, hostname, (*server)->GetLocalPort(), nullptr);
     if (*client == nullptr) {
         ADD_FAILURE() << "Failed to create client.";
         return false;
     }

     // TCP passes the client off to a new socket.
     if (protocol == Socket::Protocol::kTcp) {
         *server = (*server)->Accept();
         if (*server == nullptr) {
             ADD_FAILURE() << "Failed to accept client connection.";
             return false;
         }
     }

     return true;
 }

 // Sends a string over a Socket. Returns true if the full string (without terminating char)
 // was sent.
 static bool SendString(Socket* sock, const std::string& message) {
     return sock->Send(message.c_str(), message.length());
 }

 // Receives a string from a Socket. Returns true if the full string (without terminating char)
 // was received.
 static bool ReceiveString(Socket* sock, const std::string& message) {
     std::string received(message.length(), '\0');
     ssize_t bytes = sock->ReceiveAll(&received[0], received.length(), kTestTimeoutMs);
     return static_cast<size_t>(bytes) == received.length() && received == message;
 }

 // Tests sending packets client -> server, then server -> client.
 TEST(SocketTest, TestSendAndReceive) {
     std::unique_ptr<Socket> server, client;

     for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
         ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

         EXPECT_TRUE(SendString(client.get(), "foo"));
         EXPECT_TRUE(ReceiveString(server.get(), "foo"));

         EXPECT_TRUE(SendString(server.get(), "bar baz"));
         EXPECT_TRUE(ReceiveString(client.get(), "bar baz"));
     }
 }

 TEST(SocketTest, TestReceiveTimeout) {
     std::unique_ptr<Socket> server, client;
     char buffer[16];

     for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
         ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

         EXPECT_EQ(-1, server->Receive(buffer, sizeof(buffer), kShortTimeoutMs));
         EXPECT_TRUE(server->ReceiveTimedOut());

         EXPECT_EQ(-1, client->Receive(buffer, sizeof(buffer), kShortTimeoutMs));
         EXPECT_TRUE(client->ReceiveTimedOut());
     }

     // UDP will wait for timeout if the other side closes.
     ASSERT_TRUE(MakeConnectedSockets(Socket::Protocol::kUdp, &server, &client));
     EXPECT_EQ(0, server->Close());
     EXPECT_EQ(-1, client->Receive(buffer, sizeof(buffer), kShortTimeoutMs));
     EXPECT_TRUE(client->ReceiveTimedOut());
 }

 TEST(SocketTest, TestReceiveFailure) {
     std::unique_ptr<Socket> server, client;
     char buffer[16];

     for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
         ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

         EXPECT_EQ(0, server->Close());
         EXPECT_EQ(-1, server->Receive(buffer, sizeof(buffer), kTestTimeoutMs));
         EXPECT_FALSE(server->ReceiveTimedOut());

         EXPECT_EQ(0, client->Close());
         EXPECT_EQ(-1, client->Receive(buffer, sizeof(buffer), kTestTimeoutMs));
         EXPECT_FALSE(client->ReceiveTimedOut());
     }

     // TCP knows right away when the other side closes and returns 0 to indicate EOF.
     ASSERT_TRUE(MakeConnectedSockets(Socket::Protocol::kTcp, &server, &client));
     EXPECT_EQ(0, server->Close());
     EXPECT_EQ(0, client->Receive(buffer, sizeof(buffer), kTestTimeoutMs));
     EXPECT_FALSE(client->ReceiveTimedOut());
 }

 // Tests sending and receiving large packets.
 TEST(SocketTest, TestLargePackets) {
     std::string message(1024, '\0');
     std::unique_ptr<Socket> server, client;

     for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
         ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

         // Run through the test a few times.
         for (int i = 0; i < 10; ++i) {
             // Use a different message each iteration to prevent false positives.
             for (size_t j = 0; j < message.length(); ++j) {
                 message[j] = static_cast<char>(i + j);
             }

             EXPECT_TRUE(SendString(client.get(), message));
             EXPECT_TRUE(ReceiveString(server.get(), message));
         }
     }
 }

 // Tests UDP receive overflow when the UDP packet is larger than the receive buffer.
 TEST(SocketTest, TestUdpReceiveOverflow) {
     std::unique_ptr<Socket> server, client;
     ASSERT_TRUE(MakeConnectedSockets(Socket::Protocol::kUdp, &server, &client));

     EXPECT_TRUE(SendString(client.get(), "1234567890"));

     // This behaves differently on different systems, either truncating the packet or returning -1.
     char buffer[5];
     ssize_t bytes = server->Receive(buffer, 5, kTestTimeoutMs);
     if (bytes == 5) {
         EXPECT_EQ(0, memcmp(buffer, "12345", 5));
     } else {
         EXPECT_EQ(-1, bytes);
     }
 }

 // Tests UDP multi-buffer send.
 TEST(SocketTest, TestUdpSendBuffers) {
     std::unique_ptr<Socket> sock = Socket::NewServer(Socket::Protocol::kUdp, 0);
     std::vector<std::string> data{"foo", "bar", "12345"};
     std::vector<cutils_socket_buffer_t> buffers{{data[0].data(), data[0].length()},
                                                 {data[1].data(), data[1].length()},
                                                 {data[2].data(), data[2].length()}};
     ssize_t mock_return_value = 0;

     // Mock out socket_send_buffers() to verify we're sending in the correct buffers and
     // return |mock_return_value|.
     sock->socket_send_buffers_function_ = [&buffers, &mock_return_value](
             cutils_socket_t /*cutils_sock*/, cutils_socket_buffer_t* sent_buffers,
             size_t num_sent_buffers) -> ssize_t {
         EXPECT_EQ(buffers.size(), num_sent_buffers);
         for (size_t i = 0; i < num_sent_buffers; ++i) {
             EXPECT_EQ(buffers[i].data, sent_buffers[i].data);
             EXPECT_EQ(buffers[i].length, sent_buffers[i].length);
         }
         return mock_return_value;
     };

     mock_return_value = strlen("foobar12345");
     EXPECT_TRUE(sock->Send(buffers));

     mock_return_value -= 1;
     EXPECT_FALSE(sock->Send(buffers));

     mock_return_value = 0;
     EXPECT_FALSE(sock->Send(buffers));

     mock_return_value = -1;
     EXPECT_FALSE(sock->Send(buffers));
 }

 // Tests TCP re-sending until socket_send_buffers() sends all data. This is a little complicated,
 // but the general idea is that we intercept calls to socket_send_buffers() using a lambda mock
 // function that simulates partial writes.
 TEST(SocketTest, TestTcpSendBuffers) {
     std::unique_ptr<Socket> sock = Socket::NewServer(Socket::Protocol::kTcp, 0);
     std::vector<std::string> data{"foo", "bar", "12345"};
     std::vector<cutils_socket_buffer_t> buffers{{data[0].data(), data[0].length()},
                                                 {data[1].data(), data[1].length()},
                                                 {data[2].data(), data[2].length()}};

     // Test breaking up the buffered send at various points.
     std::list<std::string> test_sends[] = {
             // Successes.
             {"foobar12345"},
             {"f", "oob", "ar12345"},
             {"fo", "obar12", "345"},
             {"foo", "bar12345"},
             {"foob", "ar123", "45"},
             {"f", "o", "o", "b", "a", "r", "1", "2", "3", "4", "5"},

             // Failures.
             {},
             {"f"},
             {"foo", "bar"},
             {"fo", "obar12"},
             {"foobar1234"}
     };

     for (auto& test : test_sends) {
         ssize_t bytes_sent = 0;
         bool expect_success = true;

         // Create a mock function for custom socket_send_buffers() behavior. This function will
         // check to make sure the input buffers start at the next unsent byte, then return the
         // number of bytes indicated by the next entry in |test|.
         sock->socket_send_buffers_function_ = [&bytes_sent, &data, &expect_success, &test](
                 cutils_socket_t /*cutils_sock*/, cutils_socket_buffer_t* buffers,
                 size_t num_buffers) -> ssize_t {
             EXPECT_TRUE(num_buffers > 0);

             // Failure case - pretend we errored out before sending all the buffers.
             if (test.empty()) {
                 expect_success = false;
                 return -1;
             }

             // Count the bytes we've sent to find where the next buffer should start and how many
             // bytes should be left in it.
             size_t byte_count = bytes_sent, data_index = 0;
             while (data_index < data.size()) {
                 if (byte_count >= data[data_index].length()) {
                     byte_count -= data[data_index].length();
                     ++data_index;
                 } else {
                     break;
                 }
             }
             void* expected_next_byte = &data[data_index][byte_count];
             size_t expected_next_size = data[data_index].length() - byte_count;

             EXPECT_EQ(data.size() - data_index, num_buffers);
             EXPECT_EQ(expected_next_byte, buffers[0].data);
             EXPECT_EQ(expected_next_size, buffers[0].length);

             std::string to_send = std::move(test.front());
             test.pop_front();
             bytes_sent += to_send.length();
             return to_send.length();
         };

         EXPECT_EQ(expect_success, sock->Send(buffers));
         EXPECT_TRUE(test.empty());
     }
 }

 TEST(SocketMockTest, TestSendSuccess) {
     SocketMock mock;

     mock.ExpectSend("foo");
     EXPECT_TRUE(SendString(&mock, "foo"));

     mock.ExpectSend("abc");
     mock.ExpectSend("123");
     EXPECT_TRUE(SendString(&mock, "abc"));
     EXPECT_TRUE(SendString(&mock, "123"));
 }

 TEST(SocketMockTest, TestSendFailure) {
     SocketMock* mock = new SocketMock;

     mock->ExpectSendFailure("foo");
     EXPECT_FALSE(SendString(mock, "foo"));

     EXPECT_NONFATAL_FAILURE(SendString(mock, "foo"), "no message was expected");

     mock->ExpectSend("foo");
     EXPECT_NONFATAL_FAILURE(SendString(mock, "bar"), "expected foo, but got bar");
     EXPECT_TRUE(SendString(mock, "foo"));

     mock->AddReceive("foo");
     EXPECT_NONFATAL_FAILURE(SendString(mock, "foo"), "called out-of-order");
     EXPECT_TRUE(ReceiveString(mock, "foo"));

     mock->ExpectSend("foo");
     EXPECT_NONFATAL_FAILURE(delete mock, "1 event(s) were not handled");
 }

 TEST(SocketMockTest, TestReceiveSuccess) {
     SocketMock mock;

     mock.AddReceive("foo");
     EXPECT_TRUE(ReceiveString(&mock, "foo"));

     mock.AddReceive("abc");
     mock.AddReceive("123");
     EXPECT_TRUE(ReceiveString(&mock, "abc"));
     EXPECT_TRUE(ReceiveString(&mock, "123"));

     // Make sure ReceiveAll() can piece together multiple receives.
     mock.AddReceive("foo");
     mock.AddReceive("bar");
     mock.AddReceive("123");
     EXPECT_TRUE(ReceiveString(&mock, "foobar123"));
 }

 TEST(SocketMockTest, TestReceiveFailure) {
     SocketMock* mock = new SocketMock;

     mock->AddReceiveFailure();
     EXPECT_FALSE(ReceiveString(mock, "foo"));
     EXPECT_FALSE(mock->ReceiveTimedOut());

     mock->AddReceiveTimeout();
     EXPECT_FALSE(ReceiveString(mock, "foo"));
     EXPECT_TRUE(mock->ReceiveTimedOut());

     mock->AddReceive("foo");
     mock->AddReceiveFailure();
     EXPECT_FALSE(ReceiveString(mock, "foobar"));

     EXPECT_NONFATAL_FAILURE(ReceiveString(mock, "foo"), "no message was ready");

     mock->ExpectSend("foo");
     EXPECT_NONFATAL_FAILURE(ReceiveString(mock, "foo"), "called out-of-order");
     EXPECT_TRUE(SendString(mock, "foo"));

     char c;
     mock->AddReceive("foo");
     EXPECT_NONFATAL_FAILURE(mock->Receive(&c, 1, 0), "not enough bytes (1) for foo");
     EXPECT_TRUE(ReceiveString(mock, "foo"));

     mock->AddReceive("foo");
     EXPECT_NONFATAL_FAILURE(delete mock, "1 event(s) were not handled");
 }

 TEST(SocketMockTest, TestAcceptSuccess) {
     SocketMock mock;

     SocketMock* mock_handler = new SocketMock;
     mock.AddAccept(std::unique_ptr<SocketMock>(mock_handler));
     EXPECT_EQ(mock_handler, mock.Accept().get());

     mock.AddAccept(nullptr);
     EXPECT_EQ(nullptr, mock.Accept().get());
 }

 TEST(SocketMockTest, TestAcceptFailure) {
     SocketMock* mock = new SocketMock;

     EXPECT_NONFATAL_FAILURE(mock->Accept(), "no socket was ready");

     mock->ExpectSend("foo");
     EXPECT_NONFATAL_FAILURE(mock->Accept(), "called out-of-order");
     EXPECT_TRUE(SendString(mock, "foo"));

     mock->AddAccept(nullptr);
     EXPECT_NONFATAL_FAILURE(delete mock, "1 event(s) were not handled");
 }
	/*
	* Copyright (C) 2015 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	// Tests socket functionality using loopback connections. The UDP tests assume that no packets are
	// lost, which should be the case for loopback communication, but is not guaranteed.
	//
	// Also tests our SocketMock class to make sure it works as expected and reports errors properly
	// if the mock expectations aren't met during a test.

	#include "socket.h"
	#include "socket_mock.h"

	#include <list>

	#include <gtest/gtest-spi.h>
	#include <gtest/gtest.h>

	static constexpr int kShortTimeoutMs = 10;
	static constexpr int kTestTimeoutMs = 3000;

	// Creates connected sockets \|server\| and \|client\|. Returns true on success.
	bool MakeConnectedSockets(Socket::Protocol protocol, std::unique_ptr<Socket>* server,
	std::unique_ptr<Socket>* client,
	const std::string hostname = "localhost") {
	*server = Socket::NewServer(protocol, 0);
	if (*server == nullptr) {
	ADD_FAILURE() << "Failed to create server.";
	return false;
	}

	client = Socket::NewClient(protocol, hostname, (server)->GetLocalPort(), nullptr);
	if (*client == nullptr) {
	ADD_FAILURE() << "Failed to create client.";
	return false;
	}

	// TCP passes the client off to a new socket.
	if (protocol == Socket::Protocol::kTcp) {
	server = (server)->Accept();
	if (*server == nullptr) {
	ADD_FAILURE() << "Failed to accept client connection.";
	return false;
	}
	}

	return true;
	}

	// Sends a string over a Socket. Returns true if the full string (without terminating char)
	// was sent.
	static bool SendString(Socket* sock, const std::string& message) {
	return sock->Send(message.c_str(), message.length());
	}

	// Receives a string from a Socket. Returns true if the full string (without terminating char)
	// was received.
	static bool ReceiveString(Socket* sock, const std::string& message) {
	std::string received(message.length(), '\0');
	ssize_t bytes = sock->ReceiveAll(&received[0], received.length(), kTestTimeoutMs);
	return static_cast<size_t>(bytes) == received.length() && received == message;
	}

	// Tests sending packets client -> server, then server -> client.
	TEST(SocketTest, TestSendAndReceive) {
	std::unique_ptr<Socket> server, client;

	for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
	ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

	EXPECT_TRUE(SendString(client.get(), "foo"));
	EXPECT_TRUE(ReceiveString(server.get(), "foo"));

	EXPECT_TRUE(SendString(server.get(), "bar baz"));
	EXPECT_TRUE(ReceiveString(client.get(), "bar baz"));
	}
	}

	TEST(SocketTest, TestReceiveTimeout) {
	std::unique_ptr<Socket> server, client;
	char buffer[16];

	for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
	ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

	EXPECT_EQ(-1, server->Receive(buffer, sizeof(buffer), kShortTimeoutMs));
	EXPECT_TRUE(server->ReceiveTimedOut());

	EXPECT_EQ(-1, client->Receive(buffer, sizeof(buffer), kShortTimeoutMs));
	EXPECT_TRUE(client->ReceiveTimedOut());
	}

	// UDP will wait for timeout if the other side closes.
	ASSERT_TRUE(MakeConnectedSockets(Socket::Protocol::kUdp, &server, &client));
	EXPECT_EQ(0, server->Close());
	EXPECT_EQ(-1, client->Receive(buffer, sizeof(buffer), kShortTimeoutMs));
	EXPECT_TRUE(client->ReceiveTimedOut());
	}

	TEST(SocketTest, TestReceiveFailure) {
	std::unique_ptr<Socket> server, client;
	char buffer[16];

	for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
	ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

	EXPECT_EQ(0, server->Close());
	EXPECT_EQ(-1, server->Receive(buffer, sizeof(buffer), kTestTimeoutMs));
	EXPECT_FALSE(server->ReceiveTimedOut());

	EXPECT_EQ(0, client->Close());
	EXPECT_EQ(-1, client->Receive(buffer, sizeof(buffer), kTestTimeoutMs));
	EXPECT_FALSE(client->ReceiveTimedOut());
	}

	// TCP knows right away when the other side closes and returns 0 to indicate EOF.
	ASSERT_TRUE(MakeConnectedSockets(Socket::Protocol::kTcp, &server, &client));
	EXPECT_EQ(0, server->Close());
	EXPECT_EQ(0, client->Receive(buffer, sizeof(buffer), kTestTimeoutMs));
	EXPECT_FALSE(client->ReceiveTimedOut());
	}

	// Tests sending and receiving large packets.
	TEST(SocketTest, TestLargePackets) {
	std::string message(1024, '\0');
	std::unique_ptr<Socket> server, client;

	for (Socket::Protocol protocol : {Socket::Protocol::kUdp, Socket::Protocol::kTcp}) {
	ASSERT_TRUE(MakeConnectedSockets(protocol, &server, &client));

	// Run through the test a few times.
	for (int i = 0; i < 10; ++i) {
	// Use a different message each iteration to prevent false positives.
	for (size_t j = 0; j < message.length(); ++j) {
	message[j] = static_cast<char>(i + j);
	}

	EXPECT_TRUE(SendString(client.get(), message));
	EXPECT_TRUE(ReceiveString(server.get(), message));
	}
	}
	}

	// Tests UDP receive overflow when the UDP packet is larger than the receive buffer.
	TEST(SocketTest, TestUdpReceiveOverflow) {
	std::unique_ptr<Socket> server, client;
	ASSERT_TRUE(MakeConnectedSockets(Socket::Protocol::kUdp, &server, &client));

	EXPECT_TRUE(SendString(client.get(), "1234567890"));

	// This behaves differently on different systems, either truncating the packet or returning -1.
	char buffer[5];
	ssize_t bytes = server->Receive(buffer, 5, kTestTimeoutMs);
	if (bytes == 5) {
	EXPECT_EQ(0, memcmp(buffer, "12345", 5));
	} else {
	EXPECT_EQ(-1, bytes);
	}
	}

	// Tests UDP multi-buffer send.
	TEST(SocketTest, TestUdpSendBuffers) {
	std::unique_ptr<Socket> sock = Socket::NewServer(Socket::Protocol::kUdp, 0);
	std::vector<std::string> data{"foo", "bar", "12345"};
	std::vector<cutils_socket_buffer_t> buffers{{data[0].data(), data[0].length()},
	{data[1].data(), data[1].length()},
	{data[2].data(), data[2].length()}};
	ssize_t mock_return_value = 0;

	// Mock out socket_send_buffers() to verify we're sending in the correct buffers and
	// return \|mock_return_value\|.
	sock->socket_send_buffers_function_ = [&buffers, &mock_return_value](
	cutils_socket_t /cutils_sock/, cutils_socket_buffer_t* sent_buffers,
	size_t num_sent_buffers) -> ssize_t {
	EXPECT_EQ(buffers.size(), num_sent_buffers);
	for (size_t i = 0; i < num_sent_buffers; ++i) {
	EXPECT_EQ(buffers[i].data, sent_buffers[i].data);
	EXPECT_EQ(buffers[i].length, sent_buffers[i].length);
	}
	return mock_return_value;
	};

	mock_return_value = strlen("foobar12345");
	EXPECT_TRUE(sock->Send(buffers));

	mock_return_value -= 1;
	EXPECT_FALSE(sock->Send(buffers));

	mock_return_value = 0;
	EXPECT_FALSE(sock->Send(buffers));

	mock_return_value = -1;
	EXPECT_FALSE(sock->Send(buffers));
	}

	// Tests TCP re-sending until socket_send_buffers() sends all data. This is a little complicated,
	// but the general idea is that we intercept calls to socket_send_buffers() using a lambda mock
	// function that simulates partial writes.
	TEST(SocketTest, TestTcpSendBuffers) {
	std::unique_ptr<Socket> sock = Socket::NewServer(Socket::Protocol::kTcp, 0);
	std::vector<std::string> data{"foo", "bar", "12345"};
	std::vector<cutils_socket_buffer_t> buffers{{data[0].data(), data[0].length()},
	{data[1].data(), data[1].length()},
	{data[2].data(), data[2].length()}};

	// Test breaking up the buffered send at various points.
	std::list<std::string> test_sends[] = {
	// Successes.
	{"foobar12345"},
	{"f", "oob", "ar12345"},
	{"fo", "obar12", "345"},
	{"foo", "bar12345"},
	{"foob", "ar123", "45"},
	{"f", "o", "o", "b", "a", "r", "1", "2", "3", "4", "5"},

	// Failures.
	{},
	{"f"},
	{"foo", "bar"},
	{"fo", "obar12"},
	{"foobar1234"}
	};

	for (auto& test : test_sends) {
	ssize_t bytes_sent = 0;
	bool expect_success = true;

	// Create a mock function for custom socket_send_buffers() behavior. This function will
	// check to make sure the input buffers start at the next unsent byte, then return the
	// number of bytes indicated by the next entry in \|test\|.
	sock->socket_send_buffers_function_ = [&bytes_sent, &data, &expect_success, &test](
	cutils_socket_t /cutils_sock/, cutils_socket_buffer_t* buffers,
	size_t num_buffers) -> ssize_t {
	EXPECT_TRUE(num_buffers > 0);

	// Failure case - pretend we errored out before sending all the buffers.
	if (test.empty()) {
	expect_success = false;
	return -1;
	}

	// Count the bytes we've sent to find where the next buffer should start and how many
	// bytes should be left in it.
	size_t byte_count = bytes_sent, data_index = 0;
	while (data_index < data.size()) {
	if (byte_count >= data[data_index].length()) {
	byte_count -= data[data_index].length();
	++data_index;
	} else {
	break;
	}
	}
	void* expected_next_byte = &data[data_index][byte_count];
	size_t expected_next_size = data[data_index].length() - byte_count;

	EXPECT_EQ(data.size() - data_index, num_buffers);
	EXPECT_EQ(expected_next_byte, buffers[0].data);
	EXPECT_EQ(expected_next_size, buffers[0].length);

	std::string to_send = std::move(test.front());
	test.pop_front();
	bytes_sent += to_send.length();
	return to_send.length();
	};

	EXPECT_EQ(expect_success, sock->Send(buffers));
	EXPECT_TRUE(test.empty());
	}
	}

	TEST(SocketMockTest, TestSendSuccess) {
	SocketMock mock;

	mock.ExpectSend("foo");
	EXPECT_TRUE(SendString(&mock, "foo"));

	mock.ExpectSend("abc");
	mock.ExpectSend("123");
	EXPECT_TRUE(SendString(&mock, "abc"));
	EXPECT_TRUE(SendString(&mock, "123"));
	}

	TEST(SocketMockTest, TestSendFailure) {
	SocketMock* mock = new SocketMock;

	mock->ExpectSendFailure("foo");
	EXPECT_FALSE(SendString(mock, "foo"));

	EXPECT_NONFATAL_FAILURE(SendString(mock, "foo"), "no message was expected");

	mock->ExpectSend("foo");
	EXPECT_NONFATAL_FAILURE(SendString(mock, "bar"), "expected foo, but got bar");
	EXPECT_TRUE(SendString(mock, "foo"));

	mock->AddReceive("foo");
	EXPECT_NONFATAL_FAILURE(SendString(mock, "foo"), "called out-of-order");
	EXPECT_TRUE(ReceiveString(mock, "foo"));

	mock->ExpectSend("foo");
	EXPECT_NONFATAL_FAILURE(delete mock, "1 event(s) were not handled");
	}

	TEST(SocketMockTest, TestReceiveSuccess) {
	SocketMock mock;

	mock.AddReceive("foo");
	EXPECT_TRUE(ReceiveString(&mock, "foo"));

	mock.AddReceive("abc");
	mock.AddReceive("123");
	EXPECT_TRUE(ReceiveString(&mock, "abc"));
	EXPECT_TRUE(ReceiveString(&mock, "123"));

	// Make sure ReceiveAll() can piece together multiple receives.
	mock.AddReceive("foo");
	mock.AddReceive("bar");
	mock.AddReceive("123");
	EXPECT_TRUE(ReceiveString(&mock, "foobar123"));
	}

	TEST(SocketMockTest, TestReceiveFailure) {
	SocketMock* mock = new SocketMock;

	mock->AddReceiveFailure();
	EXPECT_FALSE(ReceiveString(mock, "foo"));
	EXPECT_FALSE(mock->ReceiveTimedOut());

	mock->AddReceiveTimeout();
	EXPECT_FALSE(ReceiveString(mock, "foo"));
	EXPECT_TRUE(mock->ReceiveTimedOut());

	mock->AddReceive("foo");
	mock->AddReceiveFailure();
	EXPECT_FALSE(ReceiveString(mock, "foobar"));

	EXPECT_NONFATAL_FAILURE(ReceiveString(mock, "foo"), "no message was ready");

	mock->ExpectSend("foo");
	EXPECT_NONFATAL_FAILURE(ReceiveString(mock, "foo"), "called out-of-order");
	EXPECT_TRUE(SendString(mock, "foo"));

	char c;
	mock->AddReceive("foo");
	EXPECT_NONFATAL_FAILURE(mock->Receive(&c, 1, 0), "not enough bytes (1) for foo");
	EXPECT_TRUE(ReceiveString(mock, "foo"));

	mock->AddReceive("foo");
	EXPECT_NONFATAL_FAILURE(delete mock, "1 event(s) were not handled");
	}

	TEST(SocketMockTest, TestAcceptSuccess) {
	SocketMock mock;

	SocketMock* mock_handler = new SocketMock;
	mock.AddAccept(std::unique_ptr<SocketMock>(mock_handler));
	EXPECT_EQ(mock_handler, mock.Accept().get());

	mock.AddAccept(nullptr);
	EXPECT_EQ(nullptr, mock.Accept().get());
	}

	TEST(SocketMockTest, TestAcceptFailure) {
	SocketMock* mock = new SocketMock;

	EXPECT_NONFATAL_FAILURE(mock->Accept(), "no socket was ready");

	mock->ExpectSend("foo");
	EXPECT_NONFATAL_FAILURE(mock->Accept(), "called out-of-order");
	EXPECT_TRUE(SendString(mock, "foo"));

	mock->AddAccept(nullptr);
	EXPECT_NONFATAL_FAILURE(delete mock, "1 event(s) were not handled");
	}