What is wrong with my attempts to mock a simple C++ method with googlemock?

问题

As per Patterns for unit testing a C++ method that makes a standard library call, I'm test-driving development of a network-abstracting class. In order to unit test code that makes standard C library calls (which I can't mock) to handle BSD sockets, I've defined an interface ISocket from which both my real implementation CSocket and mock MockSocket inherit.

Now I write my first unit test for the Network class, which uses an ISocket for the heavy lifting:

#include "gmock/gmock.h"
#include "gtest/gtest.h"
// C standard library includes omitted
#include "MockSocket.h"
#include "Network.h"

using ::testing::Return;
namespace JrStream {
  class NetworkTest : public ::testing::Test {
  protected:
    Network net;
    ISocket * socket_ptr;

    virtual void SetUp() {
      socket_ptr = new MockSocket();
    }
  };

  TEST_F(NetworkTest, InitCallsSocket) {
    EXPECT_CALL((MockSocket)*socket_ptr, Socket(AF_INET, SOCK_STREAM, 0))
        .Times(1)
        .WillOnce(Return(5)); //fake file descriptor

    ASSERT_TRUE(net.init(socket_ptr));
  }
} // namespace
// gtest boilerplate main() omitted

But I get this error on compilation:

g++ -g -Wall -Lgtest-1.5.0/lib -Igmock-1.5.0/include -Igtest-1.5.0/include -I.. -I../../Debug/src -c -o NetworkTest.o NetworkTest.cc
NetworkTest.cc: In member function ‘virtual void JrStream::NetworkTest_InitCallsSocket_Test::TestBody()’:
NetworkTest.cc:35: error: no matching function for call to ‘JrStream::MockSocket::MockSocket(JrStream::ISocket&)’
MockSocket.h:16: note: candidates are: JrStream::MockSocket::MockSocket()
MockSocket.h:16: note:                 JrStream::MockSocket::MockSocket(const JrStream::MockSocket&)

And here is what my interface and mock look like:

namespace JrStream {
  class ISocket {
    virtual int Socket(int domain, int type, int protocol) = 0;
  };
}

#include "gmock/gmock.h"
#include "ISocket.h"
namespace JrStream {
  class MockSocket: public JrStream::ISocket {
    MOCK_METHOD3(Socket, int(int domain, int type, int protocol));
  };
}

Any ideas what I'm doing wrong here?

回答1:

Looks like you're invoking the copy constructor for MockSocket somewhere in TestBody without a cast.

回答2:

I finally got it sorted. What was tripping me up is that I wanted to use a pointer, but googlemock works with classes. Here's what works:

#include "gmock/gmock.h"
#include "gtest/gtest.h"
// C standard library includes omitted
#include "MockSocket.h"
#include "Network.h"

using ::testing::Return;
namespace JrStream {
  class NetworkTest : public ::testing::Test {
  protected:
    Network net;
    MockSocket sock;
  };

  TEST_F(NetworkTest, InitCallsSocket) {
    EXPECT_CALL(sock, Socket(AF_INET, SOCK_STREAM, 0))
        .Times(1)
        .WillOnce(Return(5)); //fake file descriptor

    ASSERT_TRUE(net.init(&sock));
  }
} // namespace
// gtest boilerplate main() omitted

This is well and good, but I wonder how to make this work if I really needed my pointers. Sounds like an exercise for the reader. ;)

回答3:

How about:

TEST_F(NetworkTest, InitCallsSocket) {
EXPECT_CALL(*((MockSocket)*socket_ptr), Socket(AF_INET, SOCK_STREAM, 0))
    .Times(1)
    .WillOnce(Return(5)); //fake file descriptor

ASSERT_TRUE(net.init(socket_ptr));

}

(Disclaimer - I did not check if it compiles...)

来源：https://stackoverflow.com/questions/5780747/what-is-wrong-with-my-attempts-to-mock-a-simple-c-method-with-googlemock

标签

c++

unit-testing

googlemock