Unresolved externals when compiling unit tests for Visual C++ 2012 - unit-testing

Question

I want to create unit tests for a Visual C++ project. I tried following these MSDN instructions. I've found pages where they differentiate between unmanaged/mixed/pure code, but I don't fully understand those concepts. My code doesn't use .NET and would likely compile under MinGW with a few code adjustments.
My main project builds an executable, so I followed the steps under To reference exported functions from the test project. For starters I got different project options:
I went with Native Unit Test Project. I added a reference to my main project and I set Include Directories to $(SolutionDir)\Cubes;$(IncludePath). I wrote my code and got this when compiling:
1>Creating library C:\Users\Pieter\Dropbox\Unief\TTUI\TTUIproject\Cubes\Debug\CubesTest.lib and object C:\Users\Pieter\Dropbox\Unief\TTUI\TTUIproject\Cubes\Debug\CubesTest.exp
1>LayoutTest.obj : error LNK2019: unresolved external symbol "public: __thiscall Room::Room(void)" (??0Room##QAE#XZ) referenced in function "public: void __thiscall CubesTest::LayoutTest::NumOfRoomsConsistency(void)" (?NumOfRoomsConsistency#LayoutTest#CubesTest##QAEXXZ)
1>LayoutTest.obj : error LNK2019: unresolved external symbol "public: __thiscall Layout::Layout(class Room *,int)" (??0Layout##QAE#PAVRoom##H#Z) referenced in function "public: void __thiscall CubesTest::LayoutTest::NumOfRoomsConsistency(void)" (?NumOfRoomsConsistency#LayoutTest#CubesTest##QAEXXZ)
1>LayoutTest.obj : error LNK2019: unresolved external symbol "public: void __thiscall Layout::add(int,int,class Room *)" (?add#Layout##QAEXHHPAVRoom###Z) referenced in function "public: void __thiscall CubesTest::LayoutTest::NumOfRoomsConsistency(void)" (?NumOfRoomsConsistency#LayoutTest#CubesTest##QAEXXZ)
1>LayoutTest.obj : error LNK2019: unresolved external symbol "public: void __thiscall Layout::clear(int,int,bool)" (?clear#Layout##QAEXHH_N#Z) referenced in function __catch$?NumOfRoomsConsistency#LayoutTest#CubesTest##QAEXXZ$0
1>C:\Users\Pieter\Dropbox\Unief\TTUI\TTUIproject\Cubes\Debug\CubesTest.dll : fatal error LNK1120: 4 unresolved externals
If I'm not mistaken, this means that the compiler finds the header files, but not the source files. What am I missing?

Answer 1

Here is a step-by-step description on how to add an EXE as an unit-test target.
The key point is to "export" the functions/classes you want to test... You can download the complete sample here: http://blog.kalmbachnet.de/files/CPP_UnitTestApp.zip (I did not change any project settings, so all changes you can see in the source-code; of course, some parts can be made in the project settings).
Create a Win32 Application (Console or MFC or Windows, does not matter); I created a console project called CPP_UnitTestApp:
Add a function you want to test (you can also add classes). For example:
int Plus1(int i)
{
return i+1;
}
Add a header file for the functions you want to test: CPP_UnitTestApp.h
Put the declaration of the methods into the header file, and also export these functions!
#pragma once
#ifdef EXPORT_TEST_FUNCTIONS
#define MY_CPP_UNITTESTAPP_EXPORT __declspec(dllexport)
#else
#define MY_CPP_UNITTESTAPP_EXPORT
#endif
MY_CPP_UNITTESTAPP_EXPORT int Plus1(int i);
Include this header file in the main-cpp (here CPP_UnitTestApp.cpp) and define the EXPORT_TEST_FUNCTIONS before including the header:
#define EXPORT_TEST_FUNCTIONS
#include "CPP_UnitTestApp.h"
Now add a new project (Native unit test project: UnitTest1)
Include the header and the lib to the "unittest1.cpp" file (adopt the paths as you want):
#include "..\CPP_UnitTestApp.h"
#pragma comment(lib, "../Debug/CPP_UnitTestApp.lib")
Go to the project settings of the test project add add a reference to the "UnitTest1" project (Project|Properties|Common Properties|Add New Reference...: Select under "Projects" the "CPP_UnitTestApp"-Project)
Create the unit test function:
TEST_METHOD(TestMethod1)
{
int res = Plus1(12);
Assert::AreEqual(13, res);
}
Run your unit test ;)
As you can see, the main point was to export the function declaration! This is done via __declspec(dllexport) even if it is an EXE.
As I said, the demo project can be downloaded here: http://blog.kalmbachnet.de/files/CPP_UnitTestApp.zip