LNK2005 linkage error when running c++ unit test

Question

I am relatively new to c++ and I am not sure how I can resolve this error. I have a namespace QueryUtils which I am including it into another class QuerySyntaxProcessing. Below are the definitions for the following

QueryUtils.cpp

#pragma once
#include <stdio.h>
#include <string>
#include <vector>
#include <algorithm>

namespace QueryUtils
{
static const std::string SELECT_KEYWORD = "Select" + ' ';
static const std::string SUCHTHAT_KEYWORD = ' ' + "Such that";

size_t split(const std::string& txt, std::vector<std::string>& strs, char ch)
{
    size_t pos = txt.find(ch);
    size_t initialPos = 0;
    strs.clear();

    // Decompose statement
    while (pos != std::string::npos) {
        strs.push_back(txt.substr(initialPos, pos - initialPos));
        initialPos = pos + 1;

        pos = txt.find(ch, initialPos);
    }

    // Add the last one
    strs.push_back(txt.substr(initialPos, std::min(pos, txt.size()) - initialPos + 1));

    return strs.size();
}

std::string getStringBetween(const std::string& s, const std::string& start_delim, const std::string& stop_delim)
{
    unsigned first_delim_pos = s.find(start_delim);
    unsigned end_pos_of_first_delim = first_delim_pos + start_delim.length();
    unsigned last_delim_pos = s.find(stop_delim);

    return s.substr(end_pos_of_first_delim,
        last_delim_pos - end_pos_of_first_delim);
}
};

QuerySyntaxProcessing.cpp

#include "QuerySyntaxProcessing.h"
#include <ctype.h>
#include <string>
#include <vector>
#include <iostream>
#include <map>
#include "QueryUtils.cpp"

QuerySyntaxProcessing::QuerySyntaxProcessing()
{
    entityMap["stmt"] = DesignEntities::NORMAL_STATEMENT;
    entityMap["variable"] = DesignEntities::VARIABLE; 
    designEntities = { "stmt", "read", "print", "call", "while", "if", "assign", "variable", "constant", "procedure" };
}

QuerySyntaxProcessing::~QuerySyntaxProcessing()
{
}

I am omitting more details in QuerySyntaxProcessing.cpp as the methods are too long. However, I am using the namespace methods of QueryUtils in the functions for this class. I do not get any errors when building the project.

QuerySyntaxTests.cpp

#include "stdafx.h"
#include <vector>
#include <string>
#include "QuerySyntaxProcessing.h"
using namespace Microsoft::VisualStudio::CppUnitTestFramework;

namespace UnitTesting
{
    TEST_CLASS(TestPQLSytnax)
    {
    public:

        TEST_METHOD(SynonymTest) {
            QuerySyntaxProcessing* queryProcessing = new QuerySyntaxProcessing();

            vector<string> multipleVars = { "v", "a", "cd" };
            vector<string> singleVars = { "hello" };
            vector<string> wrongVars = { "54v" };
            Assert::AreEqual(queryProcessing->isSynonym(multipleVars), true);
            Assert::AreEqual(queryProcessing->isSynonym(singleVars), true);
            Assert::AreEqual(queryProcessing->isSynonym(wrongVars), false);

        }

    };
}

When I try to build the unit tests for QuerySyntaxProcessing.cpp, I get an error LNK 2005.

The error message appears when even trying to initialize the constructor for *QuerySyntaxProcessing instance. I am not double including QueryUtils.cpp header in any of the other headers. So not very sure what is wrong.

Error LNK2005 "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl QueryUtils::getStringBetween(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (?getStringBetween@QueryUtils@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@ABV23@00@Z) already defined in QueryUtilsTest.obj UnitTesting C:\Users\yicho\team16-win-spa-19s2\Team00\Code00\UnitTesting\SPA.lib(QuerySyntaxProcessing.obj) 1

Thank you all for your help..

Answer 1

In my case, you should't have the corresponding .cpp file for the unit test header. In your case, it's QuerySyntaxProcessing.cpp, you shouldn't have it. So all the implement should be written in the .h (It's not difficult with morden C++ standards).

I guess there are some global or static varibles defined in TEST_CLASS, TEST_METHOD or something like that.