Test HTML fragment parsing algorithm in template context

[nox]

https://html.spec.whatwg.org/multipage/#parsing-html-fragments

8. If the context element is a template element, push "in template" onto the stack of template insertion modes so that it is the new current template insertion mode.

[gsnedders]

So what do we need to test here? Ensuring it is on the stack of template insertion modes and hence the new current template insertion mode?

[nox]

@gsnedders Yes.