I love svelte on the personal/toy projects I've tried it on, but does someone have an example of a large-ish svelte codebase with an example of a testing patter

I love svelte on the personal/toy projects I've tried it on, but does someone have an example of a large-ish svelte codebase with an example of a testing pattern that they've found works? Using mithril/vue/react, there are assertions you can make about how a given action will modify the state, and given some state, how that state will be rendered. I've not found a good way to make assertions on the behavior of code without resorting to poking through the DOM and dealing with asynchronous behaviors.