How to start working with GTest and CMake

Question

I have recently been sold on using CMake for compiling my C   projects  and would now like to start writing some unit tests for my code  I have decided to use the Google Test utility to help with this  but require some help in getting started   All day I have been reading various guides and examples include the Primer  an introduction at IBM and some questions on SO  here and here  as well as other sources I ve lost track of  I realise there s plenty out there but somehow I am still having difficulties   I m currently trying to implement the most basic test  to confirm I ve compiled installed gtest right and it s not working  The only source file  testgtest cpp  is taken almost exactly from this previous answer    include  lt iostream gt    include  gtest gtest h   TEST sample test case  sample test        EXPECT EQ 1  1       and my associated CMakeLists txt is as follows   cmake minimum required VERSION 2 6  project basic test     Setup testing enable testing   find package GTest REQUIRED  include directories   GTEST INCLUDE DIR      Add test cpp file add executable runUnitTests     testgtest cpp      Link test executable against gtest  amp  gtest main target link libraries runUnitTests   GTEST LIBRARY DEBUG    GTEST MAIN LIBRARY DEBUG    add test      NAME runUnitTests     COMMAND runUnitTests     Note that I have chosen to link against gtest main instead of providing the main at the end of the cpp file as I believe this will allow me to scale testing up more easily to multiple files   When building the generated  sln file  in Visual C   2010 Express  I unfortunately get a long list of errors of the form  2 gt msvcprtd lib MSVCP100D dll    error LNK2005   public  virtual   thiscall std  basic iostream lt char struct std  char traits lt char gt   gt    basic iostream lt char struct std  char traits lt char gt   gt  void      1  basic iostream DU  char traits D std   std  UAE XZ  already defined in gtestd lib gtest-all obj    which I think means that I m not successfully linking to the gtest libraries  I have made sure that when linking against the debug libraries  I have then tried to build in debug mode   EDIT  Having done some more digging  I think my issue is something to do with the type of library I am building gtest into  When building gtest with CMake  if BUILD SHARED LIBS is un-checked  and I link my program against these  lib files I get the errors mentioned above  However  if BUILD SHARED LIBS is checked then I produce a set of  lib and  dll files  When now linking against these  lib files the program compiles  but when run complains that it can t find gtest dll   What are the differences between a SHARED and a not SHARED library  and if I choose not shared  why doesn t it work  Is there an option in the CMakeLists txt for my project that I am missing

User · Answer

Yours and VladLosevs  solutions are probably better than mine  If you want a brute-force solution  however  try this   SET CMAKE EXE LINKER FLAGS  NODEFAULTLIB   msvcprtd lib MSVCRTD lib     FOREACH flag var     CMAKE CXX FLAGS CMAKE CXX FLAGS DEBUG CMAKE CXX FLAGS RELEASE     CMAKE CXX FLAGS MINSIZEREL CMAKE CXX FLAGS RELWITHDEBINFO      if   flag var  MATCHES   MD           string REGEX REPLACE   MD    MT    flag var       flag var         endif   flag var  MATCHES   MD   ENDFOREACH flag var

User · Answer

I decided to throw something generic together real quick demonstrating a different way of doing it than the answers previously posted  in hope that it might help someone  The following worked for me on my mac  Firstly I ran setup commands for gtests  I just used a script I found to setup everything      usr bin env bash    install gtests script on mac   https   gist github com butuzov e7df782c31171f9563057871d0ae444a   usage   chmod  x   gtest installer sh   sudo   gtest installer sh    Current directory   THIS DIR   pwd      Downloads the 1 8 0 to disc function dl       printf   n  Downloading Google Test Archive n n      curl -LO https   github com google googletest archive release-1 8 0 tar gz     tar xf release-1 8 0 tar gz      Unpack and Build function build       printf   n  Building GTest and Gmock n n      cd googletest-release-1 8 0     mkdir build      cd        cmake -Dgtest build samples OFF -Dgtest build tests OFF         make      Install header files and library function install       printf   n  Installing GTest and Gmock n n       USR LOCAL INC   usr local include      GTEST DIR   usr local Cellar gtest       GMOCK DIR   usr local Cellar gmock        mkdir  GTEST DIR      cp googlemock gtest   a  GTEST DIR     cp -r    googletest include gtest    GTEST DIR     ln -snf  GTEST DIR  USR LOCAL INC gtest     ln -snf  USR LOCAL INC gtest libgtest a  usr local lib libgtest a     ln -snf  USR LOCAL INC gtest libgtest main a  usr local lib libgtest main a      mkdir  GMOCK DIR     cp googlemock   a    GMOCK DIR     cp -r    googlemock include gmock    GMOCK DIR     ln -snf  GMOCK DIR  USR LOCAL INC gmock     ln -snf  USR LOCAL INC gmock libgmock a  usr local lib libgmock a     ln -snf  USR LOCAL INC gmock libgmock main a  usr local lib libgmock main a      Final Clean up  function cleanup       printf   n  Running Cleanup n n       cd    THIS DIR     rm -rf   pwd  googletest-release-1 8 0     unlink   pwd  release-1 8 0 tar gz    dl  amp  amp  build  amp  amp  install  amp  amp  cleanup    Next  I made a simple folder structure and wrote some quick classes  utils    cStringUtils cpp   cStringUtils h   CMakeLists txt utils tests      gtestsMain cpp     cStringUtilsTest cpp     CMakeLists txt   I made a top level CMakeLists txt for the utils folder  and a CMakeLists txt for the tests folder  cmake minimum required VERSION 2 6   project   GTEST PROJECT  C CXX   set CMAKE C STANDARD 98  set CMAKE CXX STANDARD 98    include  h and  cpp files in util folder include directories    CMAKE CURRENT SOURCE DIR                  GTests           add subdirectory tests    This is the CMakeLists txt in the tests folder  cmake minimum required VERSION 2 6   set GTEST PROJECT gtestProject   enable testing    message  Gtest Cmake    find package GTest REQUIRED     The utils  test  and gtests directories include directories    CMAKE CURRENT SOURCE DIR    include directories   usr local Cellar gtest include   include directories   usr local Cellar gtest lib    set SOURCES   gtestsMain cpp      cStringUtils cpp   cStringUtilsTest cpp    set HEADERS      cStringUtils h    add executable   GTEST PROJECT    SOURCES   target link libraries   GTEST PROJECT  PUBLIC   gtest   gtest main    add test   GTEST PROJECT    GTEST PROJECT     Then all that s left is to write a sample gtest and gtest main  sample gtest   include  gtest gtest h   include  cStringUtils h   namespace utils    class cStringUtilsTest   public   testing  Test     public     cStringUtilsTest     m function param 10        cStringUtilsTest       protected    virtual void SetUp               declare pointer      pFooObject   new StringUtilsC               virtual void TearDown               Code here will be called immediately after each test         right before the destructor       if  pFooObject    NULL              delete pFooObject        pFooObject   NULL                StringUtilsC fooObject                  declare object   StringUtilsC  pFooObject    int m function param                    this value is used to test constructor     TEST F cStringUtilsTest  testConstructors       EXPECT TRUE 1      StringUtilsC fooObject2   fooObject     use copy constructor     fooObject fooFunction m function param     pFooObject- gt fooFunction m function param     fooObject2 fooFunction m function param           utils end   sample gtest main   include  gtest gtest h   include  cStringUtils h   int main int argc  char   argv        testing  InitGoogleTest  amp argc  argv      return RUN ALL TESTS        I can then compile and run gtests with the following commands from the utils folder  cmake   make    tests gtestProject

User · Answer

The OP is using Windows  and a much easier way to use GTest today is with vcpkg cmake     Install vcpkg as per https   github com microsoft vcpkg   and make sure you can run vcpkg from the cmd line  Take note of the vcpkg installation folder  eg  C  bin programs vcpkg   Install gtest using vcpkg install gtest  this will download  compile  and install GTest   Use a CmakeLists txt as below  note we can use targets instead of including folders   cmake minimum required VERSION 3 15  project sample CXX  enable testing   find package GTest REQUIRED  add executable test1 test cpp source cpp  target link libraries test1 GTest  GTest GTest  Main  add test test-1 test1    Run cmake with   edit the vcpkg folder if necessary  and make sure the path to the vcpkg cmake toolchain file is correct   cmake -B build -DCMAKE TOOLCHAIN FILE C  bin programs vcpkg scripts buildsystems vcpkg cmake  and build using cmake --build build as usual  Note that  vcpkg will also copy the required gtest d  dll gtest d  main dll from the install folder to the Debug Release folders   Test with cd build  amp  ctest

User · Answer

Here is a complete working example that I just tested  It downloads directly from the web  either a fixed tarball  or the latest subversion directory   cmake minimum required  VERSION 3 1   project  registerer                                        Download and install GoogleTest  include ExternalProject  ExternalProject Add gtest   URL https   googletest googlecode com files gtest-1 7 0 zip     Comment above line  and uncomment line below to use subversion      SVN REPOSITORY http   googletest googlecode com svn trunk       Uncomment line below to freeze a revision  here the one for 1 7 0      SVN REVISION -r700    PREFIX   CMAKE CURRENT BINARY DIR  gtest   INSTALL COMMAND      ExternalProject Get Property gtest source dir binary dir                      Define a test add executable registerer test registerer test cc                                            Configure the test to use GoogleTest     If used often  could be made a macro   add dependencies registerer test gtest  include directories   source dir  include  target link libraries registerer test   binary dir  libgtest a  target link libraries registerer test   binary dir  libgtest main a                                        Just make the test runnable with       make test  enable testing   add test NAME    registerer test           COMMAND registerer test

User · Answer

You can get the best of both worlds  It is possible to use ExternalProject to download the gtest source and then use add subdirectory   to add it to your build  This has the following advantages    gtest is built as part of your main build  so it uses the same compiler flags  etc  and hence avoids problems like the ones described in the question  There s no need to add the gtest sources to your own source tree    Used in the normal way  ExternalProject won t do the download and unpacking at configure time  i e  when CMake is run   but you can get it to do so with just a little bit of work  I ve written a blog post on how to do this which also includes a generalised implementation which works for any external project which uses CMake as its build system  not just gtest  You can find them here    https   crascit com 2015 07 25 cmake-gtest  https   github com Crascit DownloadProject   Update  This approach is now also part of the googletest documentation

User · Answer

Having done some more digging  I think my issue is something to do with the type of library I am building gtest into  When building gtest with CMake  if BUILD SHARED LIBS is un-checked  and I link my program against these  lib files I get the errors mentioned above  However  if BUILD SHARED LIBS is checked then I produce a set of  lib and  dll files  When now linking against these  lib files the program compiles  but when run complains that it can t find gtest dll    That is because you have to add -DGTEST LINKED AS SHARED LIBRARY 1 to compiler definitions in your project if you want to use gtest as a shared library   You could also use the static libraries  provided you compiled it with gtest force shared crt option on to eliminate errors you have seen   I like the library but adding it to the project is a real pain  And you have no chance to do it right unless  you dig  and hack  into the gtest cmake files  Shame  In particular I do not like the idea of adding gtest as a source

User · Answer

The simplest CMakeLists txt I distilled from answers in this thread and some trial and error is   project test CXX C  cmake minimum required VERSION 2 6 2    include folder contains current project s header filed include directories  include     test folder contains test files set  PROJECT SOURCE DIR test   add executable hex2base64   PROJECT SOURCE DIR  hex2base64 cpp     Link test executable against gtest nothing else required target link libraries hex2base64 gtest pthread    Gtest should already be installed on your system

User · Answer

Just as an update to  Patricia s comment in the accepted answer and  Fraser s comment for the original question  if you have access to CMake 3 11  you can make use of CMake s FetchContent function   CMake s FetchContent page uses googletest as an example   I ve provided a small modification of the accepted answer   cmake minimum required VERSION 3 11  project basic test   set GTEST VERSION 1 6 0 CACHE STRING  Google test version                                       GTest                                  FetchContent Declare googletest GIT REPOSITORY https   github com google googletest git GIT TAG release-  GTEST VERSION    FetchContent GetProperties googletest  if NOT googletest POPULATED    FetchContent Populate googletest    add subdirectory   googletest SOURCE DIR    googletest BINARY DIR   endif    enable testing                                       Unit Tests                                    Add test cpp file add executable runUnitTests testgtest cpp     Include directories target include directories runUnitTests                          lt TARGET PROPERTY gtest INTERFACE SYSTEM INCLUDE DIRECTORIES gt                          lt TARGET PROPERTY gtest main INTERFACE SYSTEM INCLUDE DIRECTORIES gt      Link test executable against gtest  amp  gtest main target link libraries runUnitTests gtest                                    gtest main   add test runUnitTests runUnitTests    You can use the INTERFACE SYSTEM INCLUDE DIRECTORIES target property of the gtest and gtest main targets as they are set in the google test CMakeLists txt script

User · Answer

Most likely  the difference in compiler options between your test binary and the Google Test library is to blame on such errors  That s why it s recommended to bring in Google Test in the source form and build it along with your tests  It s very easy to do in CMake  You just invoke  ADD SUBDIRECTORY with the path to the gtest root and then you can use public library targets  gtest and gtest main  defined there  There is more background information in this CMake thread in the googletestframework group    edit  The BUILD SHARED LIBS option is only effective on Windows for now  It specifies the type of libraries that you want CMake to build  If you set it to ON  CMake will build them as DLLs as opposed to static libs  In that case you have to build your tests with -DGTEST LINKED AS SHARED LIBRARY 1 and copy the DLL files produced by the CMake to the directory with your test binary  CMake places them in a separate output directory by default   Unless gtest in static lib doesn t work for you  it s easier not to set that option

User · Answer

The solution involved putting the gtest source directory as a subdirectory of your project  I ve included the working CMakeLists txt below if it is helpful to anyone    cmake minimum required VERSION 2 6  project basic test                                      GTest                                  ADD SUBDIRECTORY  gtest-1 6 0  enable testing   include directories   gtest SOURCE DIR  include   gtest SOURCE DIR                                       Unit Tests                                    Add test cpp file add executable  runUnitTests testgtest cpp     Link test executable against gtest  amp  gtest main target link libraries runUnitTests gtest gtest main  add test  runUnitTests runUnitTests

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