Changing GTest inclusion in cmake to use find_package (#234)

* GTest is used via find_package. No longer downloaded in cmake.

* Adding error handling

[ROCm/rccl commit: 99a491273f]

projects/rccl/test/CMakeLists.txt

@@ -11,31 +11,12 @@ if(BUILD_TESTS)
       message(FATAL_ERROR "chrpath is required for UnitTests. Please install (e.g. sudo apt-get install chrpath)")
   endif()
 
-  # Download and unpack googletest at configure time
-  configure_file(CMakeLists.txt.in googletest-download/CMakeLists.txt)
-  execute_process(
-    COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
-    RESULT_VARIABLE result
-    WORKING_DIRECTORY ${CMAKE_CURRENT_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_CURRENT_BINARY_DIR}/googletest-download)
-  if(result)
-    message(FATAL_ERROR "Build step for googletest failed: ${result}")
+  find_package(GTest REQUIRED)
+  if (NOT GTest_FOUND)
+    message(FATAL_ERROR "Please ensure GTest is installed on the system")
   endif()
 
-  # Add googletest directly to our build. This adds the following targets:
-  # gtest, gtest_main, gmock and gmock_main
-  add_subdirectory("${CMAKE_BINARY_DIR}/googletest-src"
-                   "${CMAKE_BINARY_DIR}/googletest-build")
-
-  # Add googletest directly to our build. This defines the gtest and gtest_main
-  # targets. add_subdirectory(${CMAKE_CURRENT_BINARY_DIR}/googletest-src
-  # ${CMAKE_CURRENT_BINARY_DIR}/googletest-build EXCLUDE_FROM_ALL)
+  include_directories(${GTEST_INCLUDE_DIR})  
 
   # Collect source files for tests
   set(TEST_SOURCES
@@ -55,7 +36,7 @@ if(BUILD_TESTS)
 
   add_executable(UnitTests ${TEST_SOURCES})
   target_include_directories(UnitTests PRIVATE /opt/rocm)
-  target_link_libraries(UnitTests PRIVATE gtest_main PRIVATE rccl)
+  target_link_libraries(UnitTests PRIVATE ${GTEST_LIBRARY} ${GTEST_MAIN_LIBRARY} PRIVATE rccl)
 else()
   message("Not building unit tests")
 endif()

projects/rccl/test/CMakeLists.txt.in

@@ -1,15 +0,0 @@
-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 release-1.8.1
-  SOURCE_DIR "${CMAKE_BINARY_DIR}/googletest-src"
-  BINARY_DIR "${CMAKE_BINARY_DIR}/googletest-build"
-  CONFIGURE_COMMAND ""
-  BUILD_COMMAND ""
-  INSTALL_COMMAND ""
-  TEST_COMMAND ""
-)