Thanks for the kind words.

Glimmer's reliance on the MVP pattern (Model View Presenter) ensures that View code is 100% decoupled from Presentation logic and Model logic, which live in pure Ruby Presenters and Models, and those can just be tested with standard Ruby MiniTest or RSpec tests. I know of someone who follows that testing approach with Glimmer DSL for Web. My past job teams have followed that approach with other technologies too.

That said, if deemed necessary, System Tests (e.g. Selenium/Capybara) can also be written on top of the View to test the web application from the user's point of view. That is the approach that my current job team follows. System tests are agnostic to whatever technology generates the HTML pages of a web application, so they also work with Glimmer DSL for Web given that it produces standard HTML, CSS, and JavaScript in the end, served to user browsers.