message: Make sure we're operating in not a crowded toplevel namespace.
  Don't create test structure in toplevel testing::TempDir(), but
  create our test-specific path.
diff: @@ -28,6 +28,8 @@ using testing::HasSubstr;
  #undef EXPECT_OK
  #define EXPECT_OK(value) EXPECT_TRUE((value).ok())
  +#undef ASSERT_OK
  +#define ASSERT_OK(value) ASSERT_TRUE((value).ok())
  namespace verible {
  namespace util {
  @@ -179,7 +181,8 @@ static bool CreateFsStructure(std::string_view base_dir,
  }
  TEST(FileUtil, UpwardFileSearchTest) {
  - const std::string root_dir = testing::TempDir();
  + const std::string root_dir = file::JoinPath(testing::TempDir(), "up-search");
  + ASSERT_OK(file::CreateDir(root_dir));
  ASSERT_TRUE(CreateFsStructure(root_dir, {
  "toplevel-file",
  "foo/",
  