// static random value unique for all the tests in one invocation, and the
  // current test name.
  //
  // Since the test name contains `/` (due to parameters), this function
  // replaces `/` with `_`.
  //
  // We trade in one extra initialization for readability.
  ModularFileSystemTest() {
    const std::string test_name = tensorflow::str_util::StringReplace(
        ::testing::UnitTest::GetInstance()->current_test_info()->name(), "/",