Build gtest from cmake instead of using system libs

if( WITH_TESTS STREQUAL "yes" )

   enable_testing()

   find_package( GTest )

   if( GTEST_FOUND )

      set( CXX_TESTS_FLAGS "-DHAVE_GTEST" )

   endif( GTEST_FOUND )

   # build gtest libs

   include( BuildGtest )

   # enable code coverage reports

   set( ENABLE_CODECOVERAGE ON )

# Gtest developers recommend to build the gtest libraries directly from

# the projects' build systems, see

# https://github.com/google/googletest/tree/master/googletest#incorporating-into-an-existing-cmake-project

#find_package( GTest )

#if( GTEST_FOUND )

#   set( CXX_TESTS_FLAGS "${CXX_TESTS_FLAGS} -DHAVE_GTEST" )

#endif( GTEST_FOUND )

# compatibility with the GTest package

set( GTEST_BOTH_LIBRARIES gtest gtest_main )

set( CXX_TESTS_FLAGS "${CXX_TESTS_FLAGS} -DHAVE_GTEST" )

# Download and unpack googletest at configure time

configure_file(cmake/Gtest.cmake.in googletest-download/CMakeLists.txt)

execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .

 RESULT_VARIABLE result

 WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/googletest-download )

if(result)

 message(FATAL_ERROR "CMake step for googletest failed: ${result}")

endif()

execute_process(COMMAND ${CMAKE_COMMAND} --build .

 RESULT_VARIABLE result

 WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/googletest-download )

if(result)

 message(FATAL_ERROR "Build step for googletest failed: ${result}")

endif()

# Prevent overriding the parent project's compiler/linker

# settings on Windows

set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)

# Add googletest directly to our build. This defines

# the gtest and gtest_main targets.

add_subdirectory(${CMAKE_BINARY_DIR}/googletest-src

                ${CMAKE_BINARY_DIR}/googletest-build)

# The gtest/gtest_main targets carry header search path

# dependencies automatically when using CMake 2.8.11 or

# later. Otherwise we have to add them here ourselves.

if (CMAKE_VERSION VERSION_LESS 2.8.11)

    include_directories("${gtest_SOURCE_DIR}/include")

endif()

# vim: ft=cmake

# This is a separate template for CMakeLists.txt to build gtest as a separate project

#

# Copied from upstream documentation:

# https://github.com/google/googletest/tree/master/googletest#incorporating-into-an-existing-cmake-project

cmake_minimum_required(VERSION 2.8.2)

project(googletest-download NONE)

include(ExternalProject)

ExternalProject_Add(googletest

  GIT_REPOSITORY    https://github.com/google/googletest.git

  GIT_TAG           master

  SOURCE_DIR        "${CMAKE_BINARY_DIR}/googletest-src"

  BINARY_DIR        "${CMAKE_BINARY_DIR}/googletest-build"

  CONFIGURE_COMMAND ""

  BUILD_COMMAND     ""

  INSTALL_COMMAND   ""

  TEST_COMMAND      ""

)