Use CMake's FetchContent to add gtest dependency

Author: xtofl

.travis.yml

@@ -55,7 +55,7 @@ matrix:
 
 script:
     - mkdir build && cd build
-    - cmake ..
+    - cmake ../cpp11training
     - make
     - ./cpp11training
     - cd ..

CMake/DownloadProject.CMakeLists.cmake.in

@@ -0,0 +1,24 @@
+cmake_minimum_required(VERSION 3.11.0)
+
+set(CMAKE_CXX_STANDARD 17)
+project(cpp11training)
+
+include(FetchContent)
+FetchContent_Declare(
+  googletest
+  GIT_REPOSITORY https://github.com/google/googletest.git
+  GIT_TAG        release-1.8.0
+)
+FetchContent_MakeAvailable(googletest)
+FetchContent_GetProperties(googletest)
+if(NOT googletest_POPULATED)
+  FetchContent_Populate(googletest)
+  add_subdirectory(${googletest_SOURCE_DIR} ${googletest_BINARY_DIR})
+endif()
+
+project(cpp11training)
+file (GLOB_RECURSE SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/*.cpp")
+add_executable(cpp11training ${SOURCES})
+include_directories(${CMAKE_CURRENT_SOURCE_DIR})
+target_link_libraries(cpp11training gtest gmock_main)
+# target_link_libraries(cpp11training PUBLIC GTest::main)