fixup: use external gtest

CMakeLists.txt

@@ -13,25 +13,6 @@ include(GNUInstallDirs)
 
 set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 
-##---------------------------------------------------------------------------##
-# Download and unpack googletest
-##---------------------------------------------------------------------------##
-include(FetchContent)
-FetchContent_Declare(
-  googletest
-  GIT_REPOSITORY https://github.com/google/googletest.git
-  GIT_TAG        release-1.10.0
-)
-FetchContent_GetProperties(googletest)
-if(NOT googletest_POPULATED)
-  FetchContent_Populate(googletest)
-  add_subdirectory(${googletest_SOURCE_DIR} ${googletest_BINARY_DIR})
-endif()
-
-# Prevent GoogleTest from overriding our compiler/linker options
-# when building with Visual Studio
-set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
-
 ##---------------------------------------------------------------------------##
 # Set up main options (inherit from Kokkos and Cabana CMake)
 ##---------------------------------------------------------------------------##
@@ -71,6 +52,16 @@ add_subdirectory(bin)
 ##---------------------------------------------------------------------------##
 option(CabanaMD_ENABLE_TESTING "Build tests" OFF)
 if(CabanaMD_ENABLE_TESTING)
+  find_package(GTest 1.10 REQUIRED)
+  # Workaround for FindGTest module in CMake older than 3.20
+  if(TARGET GTest::gtest)
+    set(gtest_target GTest::gtest)
+  elseif(TARGET GTest::GTest)
+    set(gtest_target GTest::GTest)
+  else()
+    message(FATAL_ERROR "bug in GTest find module workaround")
+  endif()
+
   enable_testing()
   add_subdirectory(unit_test)
 endif()

unit_test/CMakeLists.txt

@@ -1,5 +1,3 @@
-set(gtest_args --gtest_color=yes)
-
 ##--------------------------------------------------------------------------##
 ## On-node tests
 ##--------------------------------------------------------------------------##
@@ -30,7 +28,7 @@ macro(CabanaMD_add_tests)
         set(_target ${_test}_test_${_uppercase_device})
         add_executable(${_target} ${_file} ${CABANAMD_UNIT_TEST_MAIN})
         target_include_directories(${_target} PRIVATE ${_dir} ${CMAKE_CURRENT_SOURCE_DIR})
-        target_link_libraries(${_target} PRIVATE CabanaMD gtest CabanaMD)
+        target_link_libraries(${_target} PRIVATE CabanaMD ${gtest_target} CabanaMD)
 
         foreach(_np ${CABANAMD_UNIT_TEST_MPIEXEC_NUMPROCS})
           if(_device STREQUAL PTHREAD OR _device STREQUAL OPENMP)