Browser mode runs test twice in case of a self-importing svelte component

Describe the bug

So, i know this is a bit of a weird case but please bear with me.

To test components with snippets in svelte 5 i can create a snippet programmatically with createRawSnippet but that's an intentionally low level api which makes things a bit annoying to test. But today i realized that i could do something like this which is very clean and elegant.

Button.test.svelte

<script module lang="ts">
	import { expect, it } from 'vitest';
	import { render as r } from 'vitest-browser-svelte';
	import Test from './Button.test.svelte';

	it('should render a snippet in the button', async () => {
		const instance = r(Test, {
			children: rendering_this
		});

		const button = instance.getByRole('button');
		expect(button.getByText('Pretty cool eh?').query()).toBeDefined();
	});
</script>

<script lang="ts">
	import type { Snippet } from 'svelte';
	import Button from './Button.svelte';

	let { children }: { children: Snippet } = $props();
</script>

{#snippet rendering_this()}
	<b>Pretty cool eh?</b>
{/snippet}

<Button>
	{@render children()}
</Button>

so basically i can create a svelte file, name it Something.test.svelte include it in the test file and then write a test bed in the test component itself, self import it in the module and write my tests there. This works absolutely fine with @testing-library/svelte.

But i start to use vitest browser testing i have the inconvenient side effect that my tests run twice. I suspect this is a bug with vitest and it would be cool if it was fixed because i really like this pattern and i want to spread it.

Reproduction

1. Go to this stackblitz
2. run pnpm test (i think vitest browser mode is a bit glitchy on stackblitz but sometimes it works and you'll see two tests being run)

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @vitest/browser: ^2.1.8 => 2.1.8 
    vite: ^5.4.11 => 5.4.11 
    vitest: ^2.0.4 => 2.1.8

Used Package Manager

pnpm

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start with the StackBlitz reproduction, especially vite.config.ts, src/lib/Button.test.svelte, and src/lib/Button.svelte, then run pnpm test to confirm the duplicate browser-mode execution. Trace how the self-imported test component is discovered and executed, and consider the issue done when the reproduction runs its test only once.