$ git submodule add https://github.com/google/googletest.git

add_subdirectory(googletest)

target_link_libraries(test_main gtest gtest_main)

#include <gtest/gtest.h>
TEST(testSuite, test) {
  int x = 1;
  EXPECT_EQ(x, 1);
}
int main(int argc, char * * argv) {
  ::testing::InitGoogleTest(&argc, argv);
  return RUN_ALL_TESTS();
}

$ mkdir build
$ cd build
$ cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ..
$ mv compile_commands.json ..

$ cd build
$ make -j4

$ cd build
$ src/main

$ cd build
$ tests/test_main