Tweak docs and formatting.

tests/helpers.hpp

@@ -23,6 +23,8 @@ class TempDir final {
     /**
      * @brief Construct a new TempDir object.
      *
+     * On construction, the temporary directory is removed recursively from disk, then created again to ensure it is empty.
+     *
      * @param directory Path to the temporary directory (e.g., "~/data").
      */
     inline explicit TempDir(const std::filesystem::path &directory)

tests/test_all.cpp

@@ -78,6 +78,7 @@ int main(int argc, char **argv)
         fmt::print("{}\n", help_message);
         return EXIT_FAILURE;
     }
+
     // Otherwise, define argument to function mapping
     const std::unordered_map<std::string, std::function<int()>> tests = {
         {"test_args::none", test_args::none},