Here is a failing test (note the word page in an unrelated import). I tried fixing the bug but failed.

test('Updates $app/store #4', () => {
	const result = transform_svelte_code(
		`<script>
	import { page } from '$app/stores';
	import Comp from '$lib/page/Comp.svelte'
</script>

<div>{$page.url}</div>
<button onclick={() => {
	console.log($page.state);
}}></button>
`
	);
	assert.equal(
		result,
		`<script>
	import { page } from '$app/state';
	import Comp from '$lib/page/Comp.svelte'
</script>

<div>{page.url}</div>
<button onclick={() => {
	console.log(page.state);
}}></button>
`
	);
});

FYI @dummdidumm

I think it fails due to this line: https://github.com/sveltejs/cli/blob/e325bb2c71fe3fefce4cfcb07e3ab33870eddb45/packages/migrate/migrations/app-state/migrate.js#L70

Here we return early and skip the migration if the imported store alias is not prefixed with a $, unless a few conditions are met. We probably need to add another condition here (while checking for false positives) to check if the alias is part of a string or a comment.

For e.g., if a component has the following line, it won't be migrated according to the current logic:

const str = "before page after";

or

// this is a page

One thing I noticed when working on #494 was that if I ran the migration on a newly created project it would work great. However, when I changed an $app/state back to $app/stores after the initial migration, subsequent runs wouldn't fix it.

I don't know if that helps pinpoint any issues here or just muddies the waters.

That's because the word page will appear already, and that messes with the script somehow. This is basically also the testcase i mentioned above.