Linker error while unit testing with Visual Studio C++

Question

I want to unit test my C++ project with Visual Studio. After adding the folders from my project as include path to my test project, I get linker errors when trying to compile the tests:

Severity    Code    Description Project File    Line    Suppression State
Error   LNK2019 unresolved external symbol "public: __thiscall Piece::Piece(enum Color)" (??0Piece@@QAE@W4Color@@@Z) referenced in function "public: __thiscall Bishop::Bishop(enum Color)" (??0Bishop@@QAE@W4Color@@@Z)    ChessPlusPlus-Tests D:\Documents\Projects\ChessPlusPlus\ChessPlusPlus-Tests\BishopTests.obj 1   
Error   LNK2019 unresolved external symbol "public: __thiscall Board::~Board(void)" (??1Board@@QAE@XZ) referenced in function "public: void __thiscall ChessPlusPlusTests::BishopTests::ValidMovesTest(void)" (?ValidMovesTest@BishopTests@ChessPlusPlusTests@@QAEXXZ)  ChessPlusPlus-Tests D:\Documents\Projects\ChessPlusPlus\ChessPlusPlus-Tests\BishopTests.obj 1   
Error   LNK2019 unresolved external symbol "public: void __thiscall Board::placePieceAt(class Piece * const,struct Position)" (?placePieceAt@Board@@QAEXQAVPiece@@UPosition@@@Z) referenced in function "public: void __thiscall ChessPlusPlusTests::BishopTests::ValidMovesTest(void)" (?ValidMovesTest@BishopTests@ChessPlusPlusTests@@QAEXXZ)    ChessPlusPlus-Tests D:\Documents\Projects\ChessPlusPlus\ChessPlusPlus-Tests\BishopTests.obj 1   
Error   LNK2001 unresolved external symbol "public: virtual class std::vector<struct Position,class std::allocator<struct Position> > __thiscall Bishop::getMovesFor(struct Position,class Board &)" (?getMovesFor@Bishop@@UAE?AV?$vector@UPosition@@V?$allocator@UPosition@@@std@@@std@@UPosition@@AAVBoard@@@Z)   ChessPlusPlus-Tests D:\Documents\Projects\ChessPlusPlus\ChessPlusPlus-Tests\BishopTests.obj 1   
Error   LNK2001 unresolved external symbol "public: virtual class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall Bishop::toString(void)" (?toString@Bishop@@UAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)    ChessPlusPlus-Tests D:\Documents\Projects\ChessPlusPlus\ChessPlusPlus-Tests\BishopTests.obj 1   
Error   LNK2001 unresolved external symbol "public: virtual class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __thiscall Bishop::toShortString(void)" (?toShortString@Bishop@@UAE?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ)  ChessPlusPlus-Tests D:\Documents\Projects\ChessPlusPlus\ChessPlusPlus-Tests\BishopTests.obj 1   

My test source code:

#include "stdafx.h"
#include "CppUnitTest.h"
#include "Bishop.h"
#include "Board.h"
#include "TestUtils.h"

using namespace Microsoft::VisualStudio::CppUnitTestFramework;

namespace ChessPlusPlusTests
{
    TEST_CLASS(BishopTests)
    {
    public:

        TEST_METHOD(ValidMovesTest)
        {
            // Arrange
            Board board{};
            Bishop *piece = new Bishop{ Color::WHITE };
            Position pos{ 3,3 };
            board.placePieceAt(piece, pos);

            // Act
            auto validPositions = piece->getMovesFor(pos, board);

            // Assert
            TestUtils::AssertPositions(validPositions, {
                0,0,0,0,0,0,0,1,
                1,0,0,0,0,0,1,0,
                0,1,0,0,0,1,0,0,
                0,0,1,0,1,0,0,0,
                0,0,0,0,0,0,0,0,
                0,0,1,0,1,0,0,0,
                0,1,0,0,0,1,0,0,
                1,0,0,0,0,0,1,0,
            });
        }

    };
}

Without adding the include path's the test project doesn't compile, since the header file includes in the main project rely on the include paths.

The main project compiles just fine.

Can someone help me to understand whats going wrong?

Thanks!

Answer 1

I believe the chosen answer is not correct. Tests typically should be run in their environment; therefore, they should not access the implementation (.cpp)

---

When you create a separate Test Project on Visual Studio (VS 2017) you need to create a reference to the project you want to test (right-click test project -> Add -> Reference -> tick projects): Add a reference

If you see some linker errors, right-click from the Unit test project: Project->Linker->Input->Additional Dependencies->Edit then add the path to your .obj files. You could try something like "$(SolutionDir)ConsoleApplication1\$(IntDir)*.obj" where ConsoleApplication1 is the target project name.

Path to .obj

Initially, I only wanted to put a comment on Cornelis' post, but I couldn't.

Answer 2

https://www.codeproject.com/Tips/1085171/How-To-Do-Unit-Testing-with-Cplusplus-in-Visual-St

I found there that you have to add your .h and .cpp files as existing files also to the test project. That is left out on the official documentation or I missed it.

Now it works!