Run all tests without arguments

[senyai]

Hi! I find it confusing that the tests require arguments. I want to change it.

Here are my reasons:

1. Not all tests check for required arguments
   

   benchmark/test/spec_arg_test.cc

   Lines 63 to 70 in 7697796

   	bool found = false;
   	for (int i = 0; i < argc; ++i) {
   	if (strcmp("--benchmark_filter=BM_NotChosen", argv[i]) == 0) {
   	found = true;
   	break;
   	}
   	}
   	assert(found);

   and so it's easy to run a test incorrectly.
2. There are GitHub issues mentioning that a test fails when the actual problem was that the correct arguments were not passed.
3. Arguments need to be duplicated between test/CMakeLists.txt and test/BUILD and they are actually not in sync now (perf_counters_test is run with different arguments).

My solution:

1. Create test/default_arguments.h:

// ...

void AddTestArguments(int &argc, char **&argv, std::initializer_list<char const*> args={}) {
  if (argc > 1) {
    std::cout << "Warning: User is not expected to pass any command line arguments\n";
  }
  static std::vector<char const*> new_argv;
  new_argv.insert(new_argv.end(), argv, argv + argc);
  new_argv.insert(new_argv.end(), args.begin(), args.end());
  new_argv.push_back("--benchmark_min_time=0.01s");
  argv = const_cast<char**>(new_argv.data());
  argc = static_cast<int>(new_argv.size());
}

2. Call it after each main function like this

int main(int argc, char* argv[]) {
  AddTestArguments(argc, argv, {"--benchmark_counters_tabular=true"});
  benchmark::MaybeReenterWithoutASLR(argc, argv);
  RunOutputTests(argc, argv);
}

3. Cleanup the code

Sounds good?

[LebedevRI]

I want to push back on something fundamental here, ignoring the rest of the question:
by runninng the binary that is invoked during the normal test invocation,
you do not run the test, you are just running a random binary.

To run the test, you do ctest --tests-regex <...>.