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You will need to add a template called test.html that extends the "_layout.html" template. The layout template is just a wrapper template, and with the "_" in front of it, it will always be invisible to a browser.

Take a look at the twig references on extending templates. Also look at the templates supplied with the initial install to get a better idea how this works.

Twig Extend

Routes are for more refined routing of templates and you should not need a route for current implementation.

Imagine if "_layout.html" were named "_wrapper.html" and it makes a little more sense.