## Description We lack any unit tests on the Rust side; there's a fair bit of code accumulating there now, so while the Ruby specs act as a kind of integration test for the whole gem, it'd be good to have some baseline unit tests on the Rust side too. <!-- template sourced from https://gitlab.com/gitlab-org/ruby/gems/gitlab-glfm-markdown/-/blob/main/.gitlab/issue_templates/Default.md -->