googlemock giving error while building a program with mock - c++

Question

I have some experience in C and C++. But I am new to googletest and googlemock.
I am trying unit testing for C++ Programs.
I did not get any error while I was working on googletest. But, when I started working on googlemock, I got problems.
I have a simple code for working with googlemock, and when I tried to build it with the command
g++ mock.cpp -lgtest -lgtest_main -lgmock -pthread
I get this error which I am not able to understand. (I have attached both the program and the error which I got).
Please help me to understand it and overcome.
Thanks in advance.
mock.cpp
#include<iostream>
#include<vector>
#include<gtest/gtest.h>
#include<gmock/gmock.h>
using namespace std;
using ::testing::AtLeast;
using ::testing::Return;
using ::testing::_;
class DataBaseConnect{
public:
virtual bool login(string username, string password){ return true; }
virtual bool logout(string username){ return true; }
virtual int fetchRecord(){ return -1; }
};
class MockDB : public DataBaseConnect{
public:
MOCK_METHOD0(fetchRecord, int());
MOCK_METHOD1(logout, bool(string username));
MOCK_METHOD2(login, bool(string username, string password));
};
class MyDatabase{
DataBaseConnect & dbC;
public:
MyDatabase(DataBaseConnect & _dbC) : dbC(_dbC) {}
int Init(string username, string password){
if(dbC.login(username, password) != true){
cout<<"DB FAILURE\n";
return -1;
}
else{
cout<<"DB SUCCESS\n";
return 1;
}
}
};
TEST(MyDBTest, LoginTest){
//Arrange
MockDB mdb;
MyDatabase db(mdb);
EXPECT_CALL(mdb, login(_, _))
.Times(1)
.WillOnce(Return(true));
//Act
int retVal = db.Init("Terminator", "I'm Back");
//Assert
EXPECT_EQ(retVal, 1);
}
int main(int argc, char **argv){
testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}
command:
g++ mock.cpp -lgtest -lgmock -lgtest_main -pthread
error:
g++ mock.cpp -lgtest -lgmock -lgtest_main -pthread
/usr/bin/ld: /tmp/ccFl5wbu.o: in function `testing::internal::linked_ptr_internal::join(testing::internal::linked_ptr_internal const*)':
mock.cpp:(.text._ZN7testing8internal19linked_ptr_internal4joinEPKS1_[_ZN7testing8internal19linked_ptr_internal4joinEPKS1_]+0x2a): undefined reference to `testing::internal::g_linked_ptr_mutex'
/usr/bin/ld: /tmp/ccFl5wbu.o: in function `testing::internal::linked_ptr_internal::depart()':
mock.cpp:(.text._ZN7testing8internal19linked_ptr_internal6departEv[_ZN7testing8internal19linked_ptr_internal6departEv]+0x27): undefined reference to `testing::internal::g_linked_ptr_mutex'
/usr/bin/ld: /tmp/ccFl5wbu.o: in function `testing::internal::FunctionMockerBase<int ()>::InvokeWith(std::tuple<> const&)':
mock.cpp:(.text._ZN7testing8internal18FunctionMockerBaseIFivEE10InvokeWithERKSt5tupleIJEE[_ZN7testing8internal18FunctionMockerBaseIFivEE10InvokeWithERKSt5tupleIJEE]+0x33): undefined reference to `testing::internal::UntypedFunctionMockerBase::UntypedInvokeWith(void const*)'
/usr/bin/ld: /tmp/ccFl5wbu.o: in function `testing::internal::FunctionMockerBase<bool (std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)>::InvokeWith(std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&)':
mock.cpp:(.text._ZN7testing8internal18FunctionMockerBaseIFbNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEE10InvokeWithERKSt5tupleIJS7_EE[_ZN7testing8internal18FunctionMockerBaseIFbNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEE10InvokeWithERKSt5tupleIJS7_EE]+0x33): undefined reference to `testing::internal::UntypedFunctionMockerBase::UntypedInvokeWith(void const*)'
/usr/bin/ld: /tmp/ccFl5wbu.o: in function `testing::internal::FunctionMockerBase<bool (std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)>::InvokeWith(std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&)':
mock.cpp:(.text._ZN7testing8internal18FunctionMockerBaseIFbNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES7_EE10InvokeWithERKSt5tupleIJS7_S7_EE[_ZN7testing8internal18FunctionMockerBaseIFbNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES7_EE10InvokeWithERKSt5tupleIJS7_S7_EE]+0x33): undefined reference to `testing::internal::UntypedFunctionMockerBase::UntypedInvokeWith(void const*)'
/usr/bin/ld: /tmp/ccFl5wbu.o: in function `testing::internal::FunctionMockerBase<bool (std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)>::AddNewExpectation(char const*, int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::tuple<testing::Matcher<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, testing::Matcher<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)':
mock.cpp:(.text._ZN7testing8internal18FunctionMockerBaseIFbNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES7_EE17AddNewExpectationEPKciRKS7_RKSt5tupleIJNS_7MatcherIS7_EESG_EE[_ZN7testing8internal18FunctionMockerBaseIFbNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEES7_EE17AddNewExpectationEPKciRKS7_RKSt5tupleIJNS_7MatcherIS7_EESG_EE]+0xda): undefined reference to `testing::Expectation::Expectation(testing::internal::linked_ptr<testing::internal::ExpectationBase> const&)'
collect2: error: ld returned 1 exit status

Answer 1

Seems the tutorial you followed have forgotten to install gmock.so, so after building finished, you need to type sudo make install to install all the libraries file.
And the version of gtest you used is out of date, suggest to use this version:
https://github.com/google/googletest/archive/refs/tags/release-1.11.0.tar.gz
Other answers around your tutorial have also pointed out that, we need to install gmock libraries. Then the problem should be fixed.