Is there a way to test the output of +page.server routes?

[kswope]

I'm very enthusiastic about replacing the ubiquitous backend JSON API with +page.server routes (mostly because of typing and that there's no need for fetch boilerplate) but I don't see anyway to test the returned data - which is normally an essential part of writing a backend API.

For example, I have a component

<script lang="ts">
  import type { PageData } from "./$types"
  import Folders from "./Folders.svelte"
  export let data: PageData
</script>
<Folders folders={data.folders} />

In the above example, data, from +page.server.ts, is a very big and messy data structure and I'd like to get access to it for testing purposes (maybe only to snapshot it), but the only way I know of to access it in a test is after its already been rendered.

I can think of a few possible places to access it, but I'm not sure how or if its currently possible.

1. the return value of load() at +page.server.ts

export const load: PageServerLoad = async () => {
  let folders = await userBookmarkData(db.pool, 1)
  return { folders }
}

2. the automagic "data" variable in +page.svelte

<script lang="ts">
  import type { PageData } from "./$types"
  import Folders from "./Folders.svelte"
  export let data: PageData
</script>

3. a way to run whatever fetches and processes the output from the +page.server.ts route.